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jeudi 14 juin 2018

LIGHT AND SAFETY

Tech ,
LIGHT AND SAFETY

LIGHT AND SAFETY


It is established that outdoors life and property are at night safer under adequate lighting than they are under inadequate lighting. Police departments in the large cities will testify that street-lighting is a powerful ally and that crime is fostered by darkness. But in reckoning the cost of street-lighting to-day how many take into account the value of safety to life and property and the saving occasioned by the reduction in the police-force necessary to patrol the cities and towns? Owing to the necessity of darkening the streets in order to reduce the hazards of air-raids, London experienced a great increase in accidents on the streets, which demonstrated the practical value of street-lighting from the standpoint of accident prevention.
During the war, when dastardly traitors and agents of the enemy were striking at industry, the value of lighting was further recognized by the industries, with the result that flood-lighting was installed to protect them. By common consent this new phase was termed "protective lighting." Soon after the entrance of this country into the recent war, the U. S. Military Intelligence established a Section of Plant Protection which had thirty-three district offices during the war and gave attention to thirty-five thousand industrial plants engaged in production of war materials. Protective lighting was early recognized by this section as a very potential agency for defense, and extensive use was made of it. For example, Edmund Leigh, chief of the section, in discussing the value of outdoor lighting stated:
An illustration of our work in this connection is the case of an $80,000,000 powder plant of recent construction. We arranged to have all wires buried. In addition to the ordinary lighting on an adjacent hill there is a large searchlight which will command any part of the buildings and grounds. Every three hundred yards there is a watch-tower with a searchlight on top. These searchlights are for use only in emergency. Each tower has a telephone service, one connected with the other. The men in the towers have a view of the building exteriors, which are all well lighted, and the men in the buildings look across the yard to the lighted fence line and so get a silhouette of persons or objects in between. The most vital parts of the buildings are surrounded by three fences. In the near-by woods the underbrush has been cleared out and destroyed. The trunks and limbs of trees have been whitewashed. No one can walk among these trees or between the trees and the plant without being seen in silhouette.... I say flatly that I know nothing that is so potential for good defense as good illumination and at the same time so little understood.
Without such protective lighting an army of men would have been required to insure the safety of this one vital plant; still it is obvious that the cost of the protective lighting was an insignificant part of the value of the plant which it insured against damage and destruction.
The United States participated for nineteen months in the recent war and during that time about 400,000 casualties were suffered by its forces. This was at the rate of about 250,000 per year, which included casualties in battle, at sea, and from sickness, wounds, and accidents. Every one has felt the magnitude of this rate of casualties because either his home or that of a friend was blighted by one or more of these tragedies in the nineteen months. However, R. E. Simpson of the Travelers Insurance Company has stated that:
During a one-year period in this country the number of accidents due to inadequate or improper lighting exceeds the yearly rate of our war casualties.
This is a startling comparison, which emphasizes a phase of lighting that has long been recognized by experts but has been generally ignored by the industries and by the public. The condition doubtless is due largely to a lag in the proper utilization of artificial lighting behind the rapid increase in congestion in the industries and in public places.
Accident prevention is an important phase of modern life which must receive more attention. From published statistics and conservative estimates it has been concluded that there are approximately 25,000 persons killed or permanently disabled, 500,000 seriously injured, and 1,000,000 slightly injured each year in this country. Translating these figures by means of the accident severity rates, Mr. Simpson has found that there is a total of 180,000,000 days of time lost per year. This is equivalent to the loss of services of 600,000 men for a full year of 300 work-days. This loss is distributed over the entire country and consequently its magnitude is not demonstrated excepting by statistics. Of course, the causes of the accidents are numerous, but, among the means of prevention, proper lighting is important.
According to some authorities at least 18 per cent. of these accidents are due to defects in lighting. On this basis the services of 108,000 men as producers and wage-earners are continually lost at the present time because the lighting is not sufficient or proper for the safety of workers. If the full year's labor of 108,000 men could be applied to the mining of coal, 130,000,000 million tons of coal would be added to the yearly output; and only 10,000 tons would be necessary to supply adequate lighting for this army of men working for a full year for ten hours each day.
Statistics obtained under the British workmen's compensation system show that 25 per cent. of the accidents were caused by inadequate lighting of industrial plants.
Much has been said and actually done regarding the saving of fuel by curtailing lighting, but the saving may easily be converted into a great loss. For example, a 25-watt electric lamp may be operated ten hours a day for a whole year at the expense of one eighth of a ton of coal. Suppose this lamp to be over a stairway or at any vital point and that by extinguishing it there occurs a single accident which involves the loss of only one day's work on the part of the worker. If this one day's time could have produced coal, there would have been enough coal mined in the ten hours to operate the lamp for thirty-two years. The insignificant cost of lighting is also shown by the distribution of the consumption of fuel for heating, cooking, and lighting in the home. Of the total amount of fuel consumed in the home for these purposes, 87 per cent. is for heating, 11 per cent. for cooking and 2 per cent. for lighting. The amount of coal used for lighting purposes in general is about 2.5 per cent. of the total consumption of coal, so it is seen that the curtailment of lighting at best cannot save much fuel; and it may actually result in a great economic loss. By replacing inefficient lamps and accessories with efficient lighting-equipment and by washing windows and artificial lighting devices, a real saving can be realized.
Improper lighting may be as productive of accidents as inadequate lighting, and throughout the industries and upon the streets the misuse of light is in evidence. The blinding effect of a brilliant light-source is easily proved by looking at the sun. After a few moments great discomfort is experienced, and on looking away from this brilliant source the eyes are temporarily blinded by the after-images. When this happens in a factory as the result of gazing into an unshielded light-source, the workman may be injured by moving machinery, by stumbling over objects, and in many other ways. Unshaded light-sources are too prevalent in the industries. Improper lighting is likely to cause deep shadows wherein many dangers may be hidden. On the street the glare from automobile head-lamps is very prevalent and nearly everybody may testify from experience to the dangers of glare. Even the glaring locomotive head-lamp has been responsible for many casualties.
Unfortunately, natural lighting outdoors has not been under the control of man and he has accepted it as it is. The sky is a harmless source of light when viewed outdoors and the sun is in such a position that it is usually easy to avoid looking at it. It is so intensely glaring that man unconsciously avoids looking directly at it. These conditions are responsible to an extent for man's indifference and even ignorance of the rudiments of safe lighting. When he has artificial light, over which he may exercise control, he either ignores it or owing to the less striking glare he misuses it and his eyesight without realizing it. A great deal of eye-strain and permanent eye trouble arises from the abuse of the eyes by improper lighting. For example, near-sightedness is often due to inadequate illumination, which makes it necessary for the eyes to be near the work or the reading-page. Improper or inadequate lighting especially influences eyes that are immature in growth and in function, and it has been shown that with improvements in lighting the percentage of short-sightedness has decreased in the schools. Furthermore, it has been shown that where no particular attention has been given to lighting and vision, the percentage of short-sightedness has increased with the grade. There are twenty million school children in this country whose future eyesight is in the hands of those who have jurisdiction over lighting and vision. There are more than a hundred million persons in this country whose eyes are daily subjected to improper lighting-conditions, either through their own indifference or through the negligence of others.
Of a certain group of 91,000 purely industrial accidents in the year 1910, Mr. Simpson has stated that 23.8 per cent. were due, directly or indirectly, to the lack of proper illumination. These may be further divided into two approximately equal groups, one of which comprises the accidents due to inadequate illumination and the other to those toward which improper lighting was a contributing cause. The seasonal variation of these accidents is given in the following table, both for those due directly or indirectly to inadequate and improper lighting and those due to other causes.
Seasonal Distribution of Industrial Accidents Due to Lighting Conditions and to Other Causes
 Percentage due to
Lighting conditionsOther causes
July4.85.9
August5.26.2
September6.16.9
October8.68.5
November10.910.5
December15.612.2
January16.111.9
February10.010.5
March7.68.8
April6.16.9
May5.25.8
June3.85.9
The figures in one column have no direct relation to those in the other; that is, each column must be considered by itself. It is seen from the foregoing that about half the number of the accidents due to poor illumination occurred in the months of November, December, January, and February. These are the months of inadequate illumination unless artificial lighting has been given special attention. The same general type of seasonal distribution of accidents due to other causes is seen to exist but not so prominently. The greatest monthly rate of accidents during the winter season is nearly four times the minimum monthly rate during the summer for those accidents due to lighting conditions. This ratio reduces to about twice in the case of accidents due to other causes. Looking at the data from another angle, it may be considered that the likelihood of an accident being caused by lighting conditions is about twice as great in any of the four "winter" months as in any of the remaining eight months. Doubtless, this may be explained largely upon the basis of morale. The winter months are more dreary than those of summer and the workman's general outlook is different in winter than in summer. In the former season he goes back and forth to work in the dark, or at best, in the cold twilight. He is not only more depressed but he is clumsier in his heavier clothing. If the enervating influence of these factors is combined with a greater clumsiness due to cold and perhaps to colds, it is not difficult to account for this type of seasonal distribution of accidents. A study of the accidents of 1917 indicated that 13 per cent. occurred between 5 and 6 p. m.when artificial lighting is generally in use to help out the failing daylight. Only 7.3 per cent. occurred between 12 m. and 1 p. m.
When electric lighting was first introduced the public looked upon electricity as dangerous and naturally many questions pertaining to hazards arose. The distribution of electricity has been so highly perfected that little is heard of the hazards which were so magnified in the early years. Data gathered between 1884 and 1889 showed that about 13,000 fires took place in a certain district. Of these, 42 were attributed to electric wires; 22 times as many to breakage and explosion of kerosene lamps; and ten times as many through carelessness with matches. These figures cannot be taken at their face value because of the absence of data showing the relative amount of electric and kerosene lighting; nevertheless they are interesting because they represent the early period.
There are industries where unusual care must be exercised in regard to the lighting. In certain chemical industries no lamps are used excepting the incandescent lamp and this is enclosed in an air-tight glass globe. Even a public-service gas company cautions its employees and patrons thus: "Do not look for a gas-leak with a naked light! Use electric light." The coal-mine offers an interesting example of the precautions necessary because the same type of problems are found in it as in industries in general, with the additional difficulties attending the presence or possible presence of explosive gas. The surroundings in a coal-mine reflect a small percentage of the light, so that much light is wasted unless the walls are whitewashed. This is a practical method for increasing safety in coal-mines. However, the most dangerous feature is the light-source itself. According to the Bureau of Mines during the years 1916 and 1917 about 60 per cent. of the fatalities due to gas and coal-dust explosions were directly traceable to the use of defective safety lamps and to open flames.
In the early days of coal-mining it was found that the flame of a candle occasionally caused explosions in the mines. It was also found that sparks of flint and steel would not readily ignite the gas or coal-dust and this primitive device was used as a light-source. Of course, statistics are unavailable concerning the casualties in coal-mines throughout the past centuries, but with the accidents not uncommon in this scientific age, with its elaborate organizations striving to stamp out such casualties, there is good reason to believe that previous to a century or two ago the risks of coal-mining must have been great. Open flames have been widely used in this industry, but there has always been the risk of the presence or the appearance of gas or explosive dust.
The early open-flame lamps not only were sources of danger but their feeble varying intensity caused serious damage to the eyesight of miners. This factor is always present in inadequate and improper lighting, but its influence is noticeable in coal-mining in the nervous disease affecting the eyes which is known as nystagmus. The symptoms of the disease are inability to see at night and the dazzling effect of ordinary lamps. Finally objects appear to the sufferer to dance about and his vision is generally very much disturbed.
The oil-lamps used in coal-mining have a luminous intensity equivalent to about one to four candles, but owing to the atmospheric conditions in the mines a flame does not burn as brightly as in the fresh air. The possibility of explosion due to the open flame was eliminated by surrounding it with a metal gauze. Davy was the inventor of this device and his safety lamp introduced about a hundred years ago has been a boon to the coal-miner. Various improvements have been devised, but Davy's lamp contained the essentials of a safety device. The flame is surrounded by a cylinder of metal gauze which by forming a much cooler boundary prevents the mine-gas from becoming heated locally by the lamp flame to a sufficient temperature to ignite and consequently to explode. This device not only keeps the flame from igniting the gas but it also serves as an indicator of the amount of gas present, by the variation in the size and appearance of the tip of the flame. However, the gauze reduces the luminous output, and as it accumulates soot and dust the light is greatly diminished. One of these lamps is about as luminous as a candle, initially, but its intensity is often reduced by accumulations upon the gauze to only one fifth of the initial value.
The acetylene lamp is the best open-flame light-source available to the miner, for several reasons. It is of a higher candle-power than the others and as it is a burning gas, there is not the danger of flying sparks as in the case of burning wicks. The greater intensity of illumination affords a greater safety to the miner by enabling him to detect loose rock which may be ready to fall upon him. However, this lamp may be a source of danger, owing to the fact that it will burn more brilliantly in a vitiated atmosphere than other flame-lamps. Another disadvantage is the possibility of calcium carbide accidentally spilt coming in contact with water and thereby causing the generation of acetylene gas. If this is produced in the mine in sufficient quantities it is a danger which may not be suspected. If ignited it will explode and may also cause severe burns.
The electric lamp, being an enclosed light-source capable of being subdivided and fed by a small portable battery, early gave promise of solving the problem of a safe mine-lamp of adequate candle-power. Much ingenuity has been applied to the development of a portable electric safety mine-lamp, and several such lamps are now approved by the Bureau of Mines. Two general types are being manufactured, the cap outfit and the hand outfit. They consist essentially of a lamp in a reflector whose aperture is closed with a sheet or a lens of clear glass. The battery may be of the "dry" or "storage" type and in the case of the cap outfit the battery is carried on the back. The specifications for these lamps demand that a luminous intensity averaging at least 0.4 candle be maintained throughout twelve consecutive hours of operation. At no time during this period shall the output of light fall below 1.25 lumens for a cap-lamp and below 3 lumens for a hand-lamp. Inasmuch as these are equipped with reflectors, the specifications insist that a circle of light at least seven feet in diameter shall be cast on a wall twenty inches away. It appears that a portable lamp is an economic necessity in the coal-mines, on account of the expense, inconvenience, and possible dangers introduced by distribution systems such as are used in most places.
Although the major defects in lighting are due to absence of light in dangerous places, to glare, and to other factors of improper lighting, there are many minor details which may contribute to safety. For example, low lamps are useful in making steps in theaters and in other places, in drawing attention to entrances of elevators, in lighting the aisles of Pullman cars, under hand-rails on stairways, and in many other vital places. A study of accidents indicates that simple expedients are effective preventives.

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LIGHTING THE STREETS

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LIGHTING THE STREETS

LIGHTING THE STREETS


In this age of brilliantly lighted boulevards and "great white ways" flooded with light from shop-windows, electric signs, and street-lamps, it is difficult to visualize the gloom which shrouded the streets a century ago. As the belated pedestrian walks along the suburban highways in comparative safety under adequate artificial lighting, he will realize the great influence of artificial light upon civilization if he recalls that not more than two centuries ago in London
it was a common practice ... that a hundred or more in a company, young and old, would make nightly invasions upon houses of the wealthy to the intent to rob them and that when night was come no man durst adventure to walk in the streets.
Inhabitants of the cities of the present time are inclined to think that crime is common on the streets at night, but what would it be without adequate artificial light? Two centuries ago in a city like London a smoking grease-lamp, a candle, or a basket of pine knots here and there afforded the only street-lighting, and these were extinguished by eleven o'clock. Lawlessness was hatched and hidden by darkness, and even the lantern or torch served more to mark the victim than to protect him. It has been said in describing the conditions of the age of dark streets that everybody signed his will and was prepared for death before he left his home. By comparison with the present, one is again encouraged to believe that the world grows better. Doubtless, artificial light projected into the crannies has had something to do with this change.
Adequate street-lighting is really a product of the twentieth century, but throughout the nineteenth century progress was steadily made from the beginning of gas-lighting in 1807. In preceding centuries crude lighting was employed here and there but not generally by the public authorities. In the earliest centuries of written history little is said of street-lighting. In those days man was not so much inclined to improve upon nature, beyond protecting himself from the elements, and he lighted the streets more as a festive outburst than as an economic proposition. Nevertheless, in the early writings occasionally there are indications that in the centers of advanced civilization some efforts were made to light the streets.
The old Syrian city of Antioch, which in the fourth century of the Christian era contained about four hundred thousand inhabitants, appears to have had lighted streets. Libanius, who lived in the early years of that century, wrote:
The light of the sun is succeeded by other lights, which are far superior to the lamps lighted by Egyptians on the festival of Minerva of Sais. The night with us differs from the day only in the appearance of the light; with regard to labor and employment, everything goes on well.
Although apparently labor was not on a strike, the soldiers caused disturbances, for in another passage he tells of riotous soldiers who
cut with their swords the ropes from which were suspended the lamps that afforded light in the night-time, to show that the ornaments of the city ought to give way to them.
Another writer in describing a dispute between two religious adherents of opposed creeds stated that they quarreled "till the streets were lighted" and the crowd of onlookers broke up, but not until they "spat in each other's face and retired." Thus it is seen that artificial light and civilization may advance, even though some human traits remain fundamentally unchanged.
Throughout the next thousand years there was little attempt to light the streets. Iron baskets of burning wood, primitive oil-lamps, and candles were used to some extent, but during all these centuries there was no attempt on the part of the government or of individuals to light the streets in an organized manner. In 1417 the Mayor of London ordained "lanthorns with lights to bee hanged out on the winter evenings betwixt Hallowtide and Candlemasse." This was during the festive season, so perhaps street-lighting was not the sole aim. Early in the sixteenth century, the streets of Paris being infested with robbers, the inhabitants were ordered to keep lights burning in the windows of all houses that fronted on the streets.
For about three centuries the citizens of London, and doubtless of Paris and of other cities, were reminded from time to time in official mandates "on pains and penalties to hang out their lanthorns at the appointed time." The watchman in long coat with halberd and lantern in hand supplemented these mandates as he made his rounds by,
A light here, maids, hang out your lights,
And see your horns be clear and bright,
That so your candle clear may shine,
Continuing from six till nine;
That honest men that walk along
May see to pass safe without wrong.
In 1668, when some regulations were made for improving the streets of London, the inhabitants were ordered "for the safety and peace of the city to hang out candles duly to the accustomed hour." Apparently this method of obtaining lighting for the streets was not met by the enthusiastic support of the people, for during the next few decades the Lord Mayor was busy issuing threats and commands. In 1679 he proclaimed the "neglect of the inhabitants of this city in hanging and keeping out their lights at the accustomed hours, according to the good and ancient usage of this City and Acts of the Common Council on that behalf." The result of this neglect was "when nights darkened the streets then wandered forth the sons of Belial, flown with insolence and wine."
In 1694 Hemig patented a reflector which partially surrounded the open flame of a whale-oil lamp and possessed a hole in the top which aided ventilation. He obtained the exclusive rights of lighting London for a period of years and undertook to place a light before every tenth door, between the hours of six and twelve o'clock, from Michaelmas to Lady Day. His effort was a worthy one, but he was opposed by a certain faction, which was successful in obtaining a withdrawal of his license in 1716. Again the burden of lighting the streets was thrust upon the residents and fines were imposed for negligence in this respect. But this procedure after a few more years of desultory lighting was again found to be unsatisfactory.
In 1729 certain individuals contracted to light the streets of London by taxing the residents and paid the city for this monopoly. Householders were permitted to hang out a lantern or a candle or to pay the company for doing so. But robberies increased so rapidly that in 1736 the Lord Mayor and Common Council petitioned Parliament to erect lamps for lighting the city. An act was passed accordingly, giving them the privilege to erect lamps where they saw fit and to burn them from sunset to sunrise. A charge was made to the residents, on a sliding scale depending upon the rate of rental of the houses. As a consequence five thousand lamps were soon installed. In 1738 there were fifteen thousand street lamps in London and they were burned an average of five thousand hours annually.
In the annals of these early times street-lighting is almost invariably the result of an attempt to reduce the number of robberies and other crimes. In appealing for more street-lamps in 1744 the Lord Mayor and aldermen of London in a petition to the king, stated
that divers confederacies of great numbers of evil-disposed persons, armed with bludgeons, pistols, cutlasses, and other dangerous weapons, infest not only the private lanes and passages, but likewise the public streets and places of public concourse, and commit most daring outrages upon the persons of your Majesty's good subjects, whose affairs oblige them to pass through the streets, by terrifying, robbing and wounding them; and these facts are frequently perpetrated at such times as were heretofore deemed hours of security.
It has already been seen that gas-lighting was introduced in the streets of London for the first time in 1807. This marks the real beginning of public-service lighting companies. In the next decade interest in street-lighting by means of gas was awakened on the Continent, and it was not long before this new phase of civilization was well under way. Although this first gas-lighting was done by the use of open flames, it was a great improvement over all the preceding efforts. Lawlessness did not disappear entirely, of course, and perhaps it never will, but it skulked in the back streets. A controlling influence had now appeared.
But early innovations in lighting did not escape criticism and opposition. In fact, innovations to-day are not always received by unanimous consent. There were many in those early days who felt that what was good for them should be good enough for the younger generation. The descendants of these opponents are present to-day but fortunately in diminishing numbers. It has been shown that in Philadelphia in 1833 a proposal to install a gas-plant was met with a protest signed by many prominent citizens. A few paragraphs of an article entitled "Arguments against Light" which appeared in the Cologne Zeitung in 1816 indicate the character of the objections raised against street-lighting.
  1. From the theological standpoint: Artificial illumination is an attempt to interfere with the divine plan of the world, which has preordained darkness during the night-time.
  2. From the judicial standpoint: Those people who do not want light ought not to be compelled to pay for its use.
  3. From the medical standpoint: The emanations of illuminating gas are injurious. Moreover, illuminated streets would induce people to remain later out of doors, leading to an increase in ailments caused by colds.
  4. From the moral standpoint: The fear of darkness will vanish and drunkenness and depravity increase.
  5. From the viewpoint of the police: The horses will get frightened and the thieves emboldened.
  6. From the point of view of national economy: Great sums of money will be exported to foreign countries.
  7. From the point of view of the common people: The constant illumination of streets by night will rob festive illuminations of their charm.
The foregoing objections require no comment, for they speak volumes pertaining to the thoughts and activities of men a century ago. It is difficult to believe that civilization has traveled so far in a single century, but from this early beginning of street-lighting social progress received a great impetus. Artificial light-sources were feeble at that time, but they made the streets safer and by means of them social intercourse was extended. The people increased their hours of activity and commerce, industry, and knowledge grew apace.
The open gas-jet and kerosene-flame lamps held forth on the streets until within the memory of middle-aged persons of to-day. The lamplighter with his ladder is still fresh in memory. Many of the towns and villages have never been lighted by gas, for they stepped from the oil-lamp to the electric lamp. The gas-mantle has made it possible for gas-lighting to continue as a competitor of electric-lighting for the streets.
In 1877 Mr. Brush illuminated the Public Square of Cleveland with a number of arc-lamps, and these met with such success that within a short time two hundred and fifty thousand open-arc lamps were installed in this country, involving an investment of millions of dollars. Adding to this investment a much greater one in central-station equipment, a very large investment is seen to have resulted from this single development in lighting.
This open-arc lamp was the first powerful light-source available and, appearing several years before the gas-mantle, it threatened to monopolize street-lighting. It consumed about 500 watts and had a maximum luminous intensity of about 1200 candles at an angle of about 45 degrees. Its chief disadvantage was its distribution of light, mainly at this angle of 45 degrees, which resulted in a spot of light near the lamp and little light at a distance. A satisfactory street-lighting unit must emit its light chiefly just below the horizontal in those cases where the lamps must be spaced far apart for economical reasons. On referring to the chapter on the electric arc it will be seen that the upper (positive) carbon of the open-arc emits most of the light. Thus most of the light tends to be sent downward, but the lower carbon obstructs some of this with a resulting dark spot beneath the lamp.
The gas-mantle followed closely after the arrival of the carbon arc and is responsible for the existence of gas-lighting on the streets at the present time. It is a large source of light and therefore its light cannot be controlled by modern accessories as well as the light from smaller sources, such as the arc or concentrated-filament lamp. As a consequence, there is marked unevenness of illumination along the streets unless the gas-mantle units are spaced rather closely. Even with the open-arc, without special light-controlling equipment there is about a thousand times the intensity near the lamps when placed on the corners of the block as there is midway between them.
In 1879 the incandescent filament lamp was introduced and it began to appear on the streets in a short time. It was a feeble, inefficient light-source, compared with the arc-lamp, but it had the advantage of being installed on a small bracket. As a consequence of simplicity of operation, the incandescent lamp was installed to a considerable extent, especially in the suburban districts.
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THE ELECTRIC ARCS

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THE ELECTRIC ARCS

THE ELECTRIC ARCS


Early in 1800 Volta wrote a letter to the President of the Royal Society of London announcing the epochal discovery of a device now known as the voltaic pile. This letter was published in the Transactions and it created great excitement among scientific men, who immediately began active investigations of certain electrical phenomena. Volta showed that all metals could be arranged in a series so that each one would indicate a positive electric potential when in contact with any metal following it in the series. He constructed a pile of metal disks consisting of zinc and copper alternated and separated by wet cloths. At first he believed that mere contact was sufficient, but when, later, it was shown that chemical action took place, rapid progress was made in the construction of voltaic cells. The next step after his pile was constructed was to place pairs of strips of copper and zinc in cups containing water or dilute acid. Volta received many honors for his discovery, which contributed so much to the development of electrical science and art—among them a call to Paris by Bonaparte to exhibit his electrical experiments, and to receive a medal struck in his honor.
While Volta was being showered with honors, various scientific men with great enthusiasm were entering new fields of research, among which was the heating value of electric current and particularly of electric sparks made by breaking a circuit. Late in 1800 Sir Humphrey Davy was the first to use charcoal for the sparking points. In a lecture before the Royal Society in the following year he described and demonstrated that the "spark" passing between two pieces of charcoal was larger and more brilliant than between brass spheres. Apparently, he was producing a feeble arc, rather than a pure spark. In the years which immediately followed many scientific men in England, France, and Germany were publishing the results of their studies of electrical phenomena bordering upon the arc.
By subscription among the members of the Royal Society, a voltaic battery of two thousand cells was obtained and in 1808 Davy exhibited the electric arc on a large scale. It is difficult to judge from the reports of these early investigations who was the first to recognize the difference between the spark and the arc. Certainly the descriptions indicate that the simple spark was not being experimented with, but the source of electric current available at that time was of such high resistance that only feeble arcs could have been produced. In 1809 Davy demonstrated publicly an arc obtained by a current from a Volta pile of one thousand plates. This he described as "a most brilliant flame, of from half an inch to one and a quarter inches in length."
In the library of the Royal Society, Davy's notes made during the years of 1805 and 1812 are available in two large volumes. These were arranged and paged by Faraday, who was destined to contribute greatly to the future development of the science and art of electricity. In one of these volumes is found an account of a lecture-experiment by Davy which certainly is a description of the electric arc. An extract of this account is as follows:
The spark [presumably the arc], the light of which was so intense as to resemble that of the sun, ... produced a discharge through heated air nearly three inches in length, and of a dazzling splendor. Several bodies which had not been fused before were fused by this flame.... Charcoal was made to evaporate, and plumbago appeared to fuse in vacuo. Charcoal was ignited to intense whiteness by it in oxymuriatic acid, and volatilized by it, but without being decomposed.
From a consideration of his source of electricity, a voltaic pile of two thousand plates, it is certain that this could not have been an electric spark. Later in his notes Davy continued:
...the charcoal became ignited to whitness, and by withdrawing the points from each other, a constant discharge took place through the heated air, in a space at least equal to four inches, producing a most brilliant ascending arch of light, broad and conical in form in the middle.
This is surely a description of the electric arc. Apparently the electrodes were in a horizontal position and the arc therefore was horizontal. Owing to the rise of the heated air, the arc tended to rise in the form of an arch. From this appearance the term "arc" evolved and Davy himself in 1820 definitely named the electric flame, the "arc." This name was continued in use even after the two carbons were arranged in a vertical co-axial position and the arc no more "arched." An interesting scientific event of 1820 was the discovery by Arago and by Davy independently that the arc could be deflected by a magnet and that it was similar to a wire carrying current in that there was a magnetic field around it. This has been taken advantage of in certain modern arc-lamps in which inclined carbons are used. In these arcs a magnet keeps the arc in place, for without the magnet the arc would tend to climb up the carbons and go out.
In 1838 Gassiot made the discovery that the temperature of the positive electrode of an electric arc is much greater than that of the negative electrode. This is explained in electronic theory by the bombardment of the positive electrode by negative electrons or corpuscles of electricity. This temperature-difference was later taken into account in designing direct-current arc-lamps, for inasmuch as most of the light from an ordinary arc is emitted by the end of the positive electrode, this was placed above the negative electrode. In this manner most of the light from the arc is directed downward where desired. In the few instances in modern times where the ordinary direct-current arc has been used for indirect lighting, in which case the arc is above an inverted shade, the positive carbon is placed below the negative one. Gassiot first proved that the positive electrode is hotter than the negative one by striking an arc between the ends of two horizontal wires of the same substance and diameter. After the arc operated for some time, the positive wire was melted for such a distance that it bent downward, but the negative remained quite straight.
Charcoal was used for the electrodes in all the early experiments, but owing to the intense heat of the arc, it burned away rapidly. A progressive step was made in 1843 when electrodes were first made by Foucault from the carbon deposited in retorts in which coal was distilled in the production of coal-gas. However, charcoal, owing to its soft porous character, gives a longer arc and a larger flame. In 1877 the "cored" carbons were introduced. These consist of hard molded carbon rods in which there is a core of soft carbon. In these are combined the advantages of charcoal and hard carbon and the core in burning away more rapidly has a tendency to hold the arc in the center. Modern carbons for ordinary arc-lamps are generally made of a mixture of retort-carbon, soot, and coal-tar. This paste is forced through dies and the carbons are baked at a fairly high temperature. A variation in the hardness of the carbons may be obtained as the requirements demand by varying the proportions of soot and retort-carbon. Cored carbons are made by inserting a small rod in the center of the die and the carbons are formed with a hollow core. This may be filled with a softer carbon.
If two carbons connected to a source of electric current are brought together, the circuit is completed and a current flows. If the two carbons are now slightly separated, an arc will be formed. As the arc burns the carbons waste away and in the case of direct current, the positive decreases in length more rapidly than the negative one. This is due largely to the extremely high temperature of the positive tip, where the carbon fairly boils. A crater is formed at the positive tip and this is always characteristic of the positive carbon of the ordinary arc, although it becomes more shallow as the arc-length is increased. The negative tip has a bright spot to which one end of the arc is attached. By wasting away, the length of the arc increases and likewise its resistance, until finally insufficient current will pass to maintain the arc. It then goes out and to start it the carbons must be brought together and separated. The mechanisms of modern arc-lamps perform these functions automatically by the ingenious use of electromagnets.
The interior of the arc is of a violet color and the exterior is a greenish yellow. The white-hot spot on the negative tip is generally surrounded by a fringe of agitated globules which consist of tar and other ingredients of carbons. Often material is deposited from the positive crater upon the negative tip and these accretions may build up a rounded tip. This deposit sometimes interferes with the proper formation of the arc and also with the light from the arc. It is often responsible for the hissing noise, although this hissing occurs with any length of arc when the current is sufficiently increased. The hissing seems to be due to the crater enlarging under excessive current until it passes the confines of the cross-section of the carbon. It thus tends to run up the side, where it comes in contact with oxygen of the air. In this manner the carbon is directly burned instead of being vaporized, as it is when the hot crater is small and is protected from the air by the arc itself. The temperature of the positive crater is in the neighborhood of 6000° to 7000°F. The brightness of the arc under pressure is the greatest produced by artificial means and is very intense. By putting the arc under high pressure, the brightness of the sun may be attained. The temperature of the hottest spot on the negative tip is about a thousand degrees below that of the positive.
No great demand arose for arc-lamps until the development of the Gramme dynamo in 1870, which provided a practicable source of electric current. In 1876 Jablochkov invented his famous "electric candle" consisting of two rods of carbon placed side by side but separated by insulating material. In this country Brush was the pioneer in the development of open arc-lamps. In 1877 he invented an arc-lamp and an efficient form of dynamo to supply the electrical energy. The first arc-lamps were ordinary direct-current open arcs and the carbons were made from high-grade coke, lampblack, and syrup. The upper positive carbon in these lamps is consumed at a rate of one to two inches per hour. Inasmuch as about 85 per cent. of the total light is emitted by the upper (positive) carbon and most of this from the crater, the lower carbon is made as small as possible in order not to obstruct any more light than necessary. The positive carbon of the open arc is often cored and the negative is a smaller one of solid carbon. This combination operates quite satisfactorily, but sometimes solid carbons are used outdoors. The voltage across the arc is about 50 volts.
In 1846 Staite discovered that the carbons of an arc enclosed in a glass vessel into which the air was not freely admitted were consumed less rapidly than when the arc operated in the open air. After the appearance of the dynamo, when increased attention was given to the development of arc-lamps, this principle of enclosing the arcs was again considered. The early attempts in about 1880 were unsuccessful because low voltages were used and it was not until the discovery was made that the negative tip builds up considerably for voltages under 65 volts, that higher voltages were employed. In 1893 marked improvements were consummated and Jandus brought out a successful enclosed arc operating at 80 volts. Marks contributed largely to the success of the enclosed arc by showing that a small current and a high voltage of 80 to 85 volts were the requisites for a satisfactory enclosed arc.
The principle of the enclosed arc is simple. A closely fitting glass globe surrounds the arc, the fit being as close as the feeding of the carbons will permit. When the arc is struck the oxygen is rapidly consumed and the heated gases and the enclosure check the supply of fresh air. The result is that the carbons are consumed about one tenth as rapidly as in the open arc. There is no crater formed on the positive tip and the arc wanders considerably. The efficiency of the enclosed arc as a light-producer is lower than that of the open arc, but it found favor because of its slow rate of consumption of the carbons and consequent decreased attention necessary. This arc operates a hundred hours or more without trimming, and will therefore operate a week or more in street-lighting without attention. When it is considered that open arcs for all-night burning were supplied with two pairs of carbons, the second set going into use automatically when the first were consumed, the value of the enclosed arc is apparent. However, the open arc has served well and has given way to greater improvements. It is rapidly disappearing from use.
The alternating-current arc-lamp was developed after the appearance of the direct-current open-arc and has been widely used. It has no positive or negative carbons, for the alternating current is reversing in direction usually at the rate of 120 times per second; that is, it passes through 60 complete cycles during each second. No marked craters form on the tips and the two carbons are consumed at about the same rate. The average temperature of the carbon tips is lower than that of the positive tip of a direct-current arc, with the result that the luminous efficiency is lower. These arcs have been made of both the open and enclosed type. They are characterized by a humming noise due to the effect of alternating current upon the mechanism and also upon the air near the arc. This humming sound is quite different from the occasional hissing of a direct-current arc. When soft carbons are used, the arc is larger and apparently this mass of vapor reduces the humming considerably. The humming is not very apparent for the enclosed alternating-current arc. The alternating arc can easily be detected by closely observing moving objects. If a pencil or coin be moved rapidly, a number of images appear which are due to the pulsating character of the light. At each reversal of the current, the current reaches zero value and the arc is virtually extinguished. Therefore, there is a maximum brightness midway between the reversals.
Various types of all these arcs have been developed to meet the different requirements of ordinary lighting and to adapt this method of light-production to the needs of projection, stage-equipment, lighthouses, search-lights, and other applications.
Up to this point the ordinary carbon arc has been considered and it has been seen that most of the light is emitted by the glowing end of the positive carbon. In fact, the light from the arc itself is negligible. A logical step in the development of the arc-lamp was to introduce salts in order to obtain a luminous flame. This possibility as applied to ordinary gas-flames had been known for years and it is surprising that it had not been early applied to carbons. Apparently Bremer in 1898 was the first to introduce fluorides of calcium, barium, and strontium. The salts deflagrate and a luminous flame envelops the ordinary feeble arc-flame. From these arcs most of the light is emitted by the arc itself, hence the name "flame-arcs."
By the introduction of metallic salts into the carbons the possibilities of the arc-lamp were greatly extended. The luminous output of such lamps is much greater than that of an ordinary carbon arc using the same amount of electrical energy. Furthermore, the color or spectral character of the light may be varied through a wide range by the use of various salts. For example, if carbons are impregnated with calcium fluoride, the arc-flame when examined by means of a spectroscope will be seen to contain the characteristic spectrum of calcium, namely, some green, orange, and red rays. These combine to give to this arc a very yellow color. As explained in a previous chapter, the salts for this purpose may be wisely chosen from a knowledge of their fundamental or characteristic flame-spectra.
These lamps have been developed to meet a variety of needs and their luminous efficiencies range from 20 to 40 lumens per watt, being several times that of the ordinary carbon open-arc. The red flame-arc owes its color chiefly to strontium, whose characteristic visible spectrum consists chiefly of red and yellow rays. Barium gives to the arc a fairly white color. The yellow and so-called white flame-arcs have been most commonly used. Flame-arcs have been produced which are close to daylight in color, and powerful blue-white flame-arcs have satisfied the needs of various chemical industries and photographic processes. These arcs are generally operated in a space where the air-supply is restricted similar to the enclosed-arc principle. Inasmuch as poisonous fumes are emitted in large quantities from some flame-arcs, they are not used indoors without rather generous ventilation. In fact, the flame-arcs are such powerful light-sources that they are almost entirely used outdoors or in very large interiors especially of the type of open factory buildings. They are made for both direct and alternating current and the mechanisms have been of several types. The electrodes are consumed rather rapidly so they are made as long as possible. In one type of arc, the carbons are both fed downward, their lower ends forming a narrow V with the arc-flame between their tips. Under these conditions the arc tends to travel vertically and finally to "stretch" itself to extinction. However, the arc is kept in place by means of a magnet above it which repels the arc and holds it at the ends of the carbons.
The chief objection to the early flame-arcs was the necessity for frequent renewal of the carbons. This was overcome to a large extent in the Jandus regenerative lamp in which the arc operates in a glass enclosure surrounded by an opal globe. However, in addition to the inner glass enclosure, two cooling chambers of metal are attached to it. Air enters at the bottom and the fumes from the arc pass upward and into the cooling chambers, where the solid products are deposited. The air on returning to the bottom is thus relieved of these solids and the inner glass enclosure remains fairly clean. The lower carbon is impregnated with salts for producing the luminous flame and the upper carbon is cored. The life of the electrodes is about seventy-five hours.
The next step was the introduction of the so-called "luminous-arc" which is a "flame-arc" with entirely different electrodes. The lower (negative) electrode consists of an iron tube packed chiefly with magnetite (an iron oxide) and titanium oxide in the approximate proportions of three to one respectively. The magnetite is a conductor of electricity which is easily vaporized. The arc-flame is large and the titanium gives it a high brilliancy. The positive electrode, usually the upper one, is a short, thick, solid cylinder of copper, which is consumed very slowly. This lamp, known as the magnetite-arc, has a luminous efficiency of about 20 lumens per watt with a clear glass globe.
The mechanisms which strike the arc and feed the carbons are ingenious devices of many designs depending upon the kind of arc and upon the character of the electric circuit to which it is connected. Late developments in electric incandescent filament lamps have usurped some of the fields in which the arc-lamp reigned supreme for years and its future does not appear as bright now as it did ten years ago. High-intensity arcs have been devised with small carbons for special purposes and considered as a whole a great amount of ingenuity has been expended in the development of arc-lamps. There will be a continued demand for arc-lamps, for scientific developments are opening new fields for them. Their value in photo-engraving, in the moving-picture production studios, in moving-picture projection, and in certain aspects of stage-lighting is firmly established, and it appears that they will find application in certain chemical industries because the arc is a powerful source of radiant energy which is very active in its effects upon chemical reactions.
The luminous efficiencies of arc-lamps depend upon so many conditions that it is difficult to present a concise comparison; however, the following may suffice to show the ranges of luminous output per watt under actual conditions of usage. These efficiencies, of course, are less than the efficiencies of the arc alone, because the losses in the mechanism, globes, etc., are included.
 Lumens per watt
Open carbon arc4 to 8
Enclosed carbon arc7
Enclosed flame-arc (yellow or white)15 to 25
Luminous arc10 to 25
Another lamp differing widely in appearance from the preceding arcs may be described here because it is known as the mercury-arc. In this lamp mercury is confined in a transparent tube and an arc is started by making and breaking a mercury connection between the two electrodes. The arc may be maintained of a length of several feet. Perhaps the first mercury-arc was produced in 1860 by Way, who permitted a fine jet of mercury to fall from a reservoir into a vessel, the reservoir and receiver being connected to the poles of a battery. The electric current scattered the jet and between the drops arcs were formed. He exhibited this novel light-source on the mast of a yacht and it received great attention. Later, various investigators experimented on the production of a mercury-arc and the first successful ones were made in the form of an inverted U-tube with the ends filled with mercury and the remainder of the tube exhausted.
Cooper Hewitt was a successful pioneer in the production of practicable mercury-arcs. He made them chiefly in the form of straight tubes of glass up to several feet in length, with enlarged ends to facilitate cooling. The tubes are inclined so that the mercury vapor which condenses will run back into the enlarged end, where a pool of mercury forms the negative electrode. The arc may be started by tilting the tube so that a mercury thread runs down the side and connects with the positive electrode of iron. The heat of the arc volatilizes the mercury so that an arc of considerable length is maintained. The tilting is done by electromagnets. Starting has also been accomplished by means of a heating coil and also by an electric spark. The lamps are stabilized by resistance and inductance coils.
One of the defects of the light emitted by the incandescent vapor of mercury is its paucity of spectral colors. Its visible spectrum consists chiefly of violet, blue, green, and yellow rays. It emits virtually no red rays, and, therefore, red objects appear devoid of red. The human face appears ghastly under this light and it distorts colors in general. However, it possesses the advantages of high efficiency, of reasonably low brightness, of high actinic value, and of revealing detail clearly. Various attempts have been made to improve the color of the light by adding red rays. Reflectors of a fluorescent red dye have been used with some success, but such a method reduces the luminous efficiency of the lamp considerably. The dye fluoresces red under the illumination of ultra-violet, violet, and blue rays; that is, it has the property of converting radiation of these wave-lengths into radiant energy of longer wave-lengths. By the use of electric incandescent filament lamps in conjunction with mercury-arcs, a fairly satisfactory light is obtained. Many experiments have been made by adding other substances to the mercury, such as zinc, with the hope that the spectrum of the other substance would compensate the defects in the mercury spectrum. However no success has been reached in this direction.
By the use of a quartz tube which can withstand a much higher temperature than glass, the current density can be greatly increased. Thus a small quartz tube of incandescent mercury vapor will emit as much light as a long glass tube. The quartz mercury-arc produces a light which is almost white, but the actual spectrum is very different from that of white sunlight. Although some red rays are emitted by the quartz arc, its spectrum is essentially the same as that of the glass-tube arc. Quartz transmits ultra-violet radiation, which is harmful to the eyes, and inasmuch as the mercury vapor emits such rays, a glass globe should be used to enclose the quartz tube when the lamp is used for ordinary lighting purposes.
It is fortunate that such radically different kinds of light-sources are available, for in the complex activities of the present time all are in demand. The quartz mercury-arc finds many isolated uses, owing to its wealth of ultra-violet radiation. It is valuable as a source of ultra-violet for exciting phosphorescence, for examining the transmission of glasses for this radiation, for sterilizing water, for medical purposes, and for photography.

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DUCK SHOOTING.

Tech ,
DUCK SHOOTING.

DUCK SHOOTING.


Alured's thirteenth birthday was on the 10th of January, and he had extracted a promise from Fulk, to take him duck-shooting to the mouth of our little river.
Nothing can be prettier than our tide river by day, with the retreating banks overhung with trees, the long-legged herons standing in the firs, looking like toys in a German box; while the breadth of blue water reflects the trees that bend down to it.
But, on a winter's night, to creep in perfect silence and lie still under an overhanging bank, not daring to make a sound, till you could get a shot at the ducks disporting themselves in the moonlight, on the frozen mud on the banks! Such an occupation could only be endurable under the name of sport.
However, Fulk and Bertram had had their time, and now Alured was having the infection in his turn; but Trevor was driven over to spend the day, much mortified that he had a bad broken chilblain, which made his boots unwearable, and it was the more disappointing, that it was a very hard frost, and there was a report that some wild swans had been seen on the river.
But in the course of the day Jaquetta routed out a pair of India rubber boots which, with worsted stockings beneath, did not press the chilblains at all, and after having spent all the day in snow-balling and building forts, Trevor declared himself far from lame, and resolved not to lose the fun. He had not come equipped, so Alured put him into an old grey coat and cap of his own, and merrily they started in the frosty moonlight, with dashes of snow lying under the hedges, and everything intensely light. Fulk grumbling in fun at being dragged away from his warm fire, and pretending to be grown old, the boys shouting to one another full of glee, all the dogs in the yard clamouring because only the wise old retriever, Captain, was allowed to be of the party; Arthur Cradock making ridiculous mistakes on purpose between the uncle and nephew, Trevorsham and Sham Trevor, as he called them.
Alas! Nay, shall I say alas, or only be thankful?
They had been gone some time when we heard a rapid tread coming towards the porch. Something in the very sound thrilled Jaquetta and me at once with dismay. We darted out, and saw Brand, the head gamekeeper in the park.
"Never fear, my lady; thank God," he said, "my lord is quite safe. It is poor Master Lea who is hurt; and Mr. Torwood sent me up for some brandy, and a mattress, and a lantern, and some cloths."
That assured us that he was alive, and we ran to fulfil the request in the utmost haste, without asking further questions, and sending off Sisson to ride for the poor mother, and to go on to Shinglebay for the doctor, though, to our comfort, we knew that Arthur had almost finished his surgical education, and was sure to know what was to be done.
"A stray shot," we said again and again to each other; and we called Nurse Rowe, and made up a bed in Alured's old nursery, and lighted a fire, and were all ready, with hearts beating heavy with suspense before the steps came back—my poor Alured first, as we held the door open. How pale his face looked! and his brows were drawn with horror, and his steps dragging, saying not a word, but trembling, as he came and held by me, with one hand on my waist, while Fulk and Sisson carried in the mattress, Arthur Cradock at the side, and Perrault, who had joined them, walking behind with the flask.
Dear Trevor lay white with sobbing breath and closed eyes, the cloths and mattress soaked through and through with blood. They put him down on the keeping-room table, and Arthur poured more brandy into his mouth.
I said something of the room being ready but Arthur said very low "He is dying—internal bleeding;" and when Jaquetta asked "Can nothing be done?" he answered, "Nothing but to leave him still."
"Trevorsham," murmured the feeble voice, and Alured was close to him; "Ally! you are all right!" and then again, as Alured assured him he would be better— "No, I shan't; I'm so glad it wasn't you. I always thought he'd do it some day, and now you're quite safe, I want to thank God."
We did not understand those words then; we did soon.
The weak voice rambled on, "to thank God; but oh, it hurts so—I can't—I will when I get there." Then presently "Mother!"
"She'll come very soon," said Alured.
"Mother! oh, mother! Trevorsham, don't let them know. O Trev, promise, promise!"
"Promise what? I promise, whatever it is! Only tell me," entreated Alured.
"Take care of her—of mother. Don't let—" and then his eyes met Perrault's, and a shudder came all over him, which brought the end nearer; and all another spoonful of brandy could do was to enable him to say something in Alured's ear, and then a broken word or two—"forgive—glad—pray;" and when we all knelt and Fulk did say the Lord's Prayer, and a verse or two more, there was a peaceful loving look at Fulk and Jaquetta and me, and then the whisper of the Name that is above every name, as a glad brightness came over the face, and the eyes looked upwards, and so grew set in their gaze, and there was the sound one never can forget.
Nurse Rowe laid her hand on Alured's neck, as he knelt with his head close to Trevor's. Fulk and I looked at each other, and we knew that all was over.
They had tried in vain to check the bleeding. No one could have done more than Arthur had done, but a main artery had been injured, and nothing could have saved him. He had said nothing after the first cry, except when he saw Alured's grief. "Never mind; I'm glad it was not you." And once or twice, as they carried him home, he had begged to be put down, though they durst not attend to the entreaty, and Arthur did not think he had suffered much pain.
It jarred that just as we would have knelt for one silent prayer, Perrault's voice broke on us. "Ah! poor boy, it is better than if it lasted longer! I saw that half-witted fellow, Billy Blake about. So I don't wonder at anything; but of course it was a mere accident, and I shall not press it."
Scarcely hearing him, I had joined Mrs. Rowe in the endeavour to detach Alured from his dear companion, when there was poor Hester among us, with open horror-stricken eyes, and a wild, frightful shriek as she leapt forward; and no words can describe the misery of her voice as she called on her boy to look at her, and speak to her—gathering him into her bosom with a passionate, desperate clasp, that seemed almost an outrage on the calm awful stillness of the innocent child; and Alured involuntarily cried, "Oh, don't," while Fulk spoke to her kindly; but just then she saw her husband, and sprang on her feet, her eyes flashing, her hands stretched out, while she screamed out, "You here? You dare to come here? You, who killed him!" Fulk caught her arm, saying, "Hush! Hester; come away. It was a lamentable accident, but—"
"Oh!" the laugh she gave was the most horrible thing I ever heard. "Accident! I tell you it has been his one thought to make accidents for Trevorsham! And he hated my child—my dear, noble, beautiful, only one! He made him miserable, and murdered him at last!"
She gave another passionate kiss to the cheeks, and then just as I hoped she was going to let us lead her away, she darted from us, rushed past Mr. Cradock who was entering the porch, and in another moment, he hurrying after her, saw her rush down the steep grassy slope, and fling herself into the swollen rapid stream.
His shout brought them all out, and Fulk found him too in the river, holding her, and struggling with the stream, which winter had made full and violent, and the black darkness of the shadows made it hard to find any landing place, and he was nearly swept away before it was possible to get them out of the river; and Fulk was as completely drenched as he was when they brought poor Hester, quite unconscious, up to the house, and brought her to the room that had been prepared for her son; and there Dr. Brown and Arthur gave us plenty to do in filling hot-water baths and warming flannels, or rubbing the icy hands and feet. Only that constant need of exertion could have borne us through the horror of it all. But it was not over yet. There was a call of "Ursula," and as I ran down, I found Fulk standing at the bottom of the stairs with Alured in his arms looking like death!
"I found him on the parlour sofa, the little window and the escritoire open!" Fulk said breathlessly, "the villain!"
"I'm not hurt," said dear Alured's voice, faintly, but reassuringly, "Oh! put me down, Fulk."
We did put him down on the floor—there was no other place—with his head on my lap, and I found strange voices asking him what Perrault had done to him. "Oh! nothing! 'twasn't that. Yes, he's gone, out by the window."
He swallowed some wine and then sat up, leaning against me as I sat at the bottom of the stairs, quite himself again, and assuring us that he was not hurt; Perrault never touched him—"Threatened you, then," said Fulk.
"No," said Alured, as if he hadn't spirit to be indignant; "I meant him to get off."
"Lord Trevorsham!" cried a voice in great displeasure, and I saw that Mr. Halsted, the nearest magistrate, was standing over us.
"He told me—Trevor did"—said Alured.
"Told you to assist the murderer to escape!" exclaimed Mr. Halsted.
Alured let his head fall back, and would not answer, and Fulk said, "There is no need for him to speak at present, is there? The constable and the rest are gone after Perrault, but I do not yet know what has directed the suspicion against him."
And then at the stair foot, for there was no other place to go to, we came to an understanding, the two gentlemen and Brand the keeper standing, and I seated on the step with my boy lying against me. I could not trust him out of my sight, nor, indeed, was he fit to be left.
It seems that Brand had been uneasy about the number of shooters whom the report of the swans had attracted; and though the bank of the river was not Trevorsham ground, he had kept along on the border of the covers higher up the hill, to guard his hares and pheasants.
Thus he had seen everything distinctly in the moonlight against the snowy bank below; and he had observed one figure in particular, moving stealthily along, in a parallel line with that which he knew our party would take, though they were in shadow, and he could not see them.
Suddenly, a chance shot fired somewhere made all the ducks fly up. A head and shoulders that Brand took for his young lord's, appeared beyond the shadow, beside Fulk's; and, at the same moment, he saw the man whom he had been watching level his gun from behind, and fire. Then came the cry, and Brand running down in horror himself, was amazed to see this person doing the same, and when they came up with the group, he recognised Perrault; and found, at the same time, that Trevor was the sufferer, and that Lord Trevorsham was safe. He then would have thought it an accident, but for Perrault's own needless wonder, whence the shot came, and that same remark, that Billy Blake, the half-witted son of a farmer, was about that night.
Brand, a shrewd fellow, restrained his reply, that Mr. Perrault knew most about it himself. He saw that the most pressing need was to obey Fulk in fetching necessaries from our house, and that Perrault meant to disarm suspicion by treating it as an accident, so he thought it best to go off to a magistrate with his story, before giving any alarm; feeling certain, as he said, that the shot had been meant for the Earl; as indeed, Perrault's first exclamation on coming up showed that he too had expected to find Trevorsham the wounded one.
Mr. Halsted had sent for the constable and came at once, though even then inclined to doubt whether Brand had not imputed accident to malice. But Perrault's flight had settled that question. During the confusion, while Hester was being carried upstairs, the miscreant had the opportunity of speaking to the child.
"Drowned! No, she is not drowned; but she may be the other thing if you don't get me off! What, don't you understand? Let the law lay a finger on me, and what is to hinder me from telling how your sweet sister has been plotting to get you—yes, you, out of the way of her darling. No, you needn't fear, there's nothing to get by it now. Lucky for you you brought the poor boy out, when I thought him safe by the fire nursing his chilblain. But mind this, if I am arrested, all the story shall come out. I'll not swing alone. If I fired, she pointed the gun! And you may judge if that was what poor Trevor meant by his mutterings to you about 'mother.'"
"But what do you want?" Alured asked. He had backed up against the wall; he was past being frightened, but he felt numb and sick with horror, and ready to do anything to get the wretch out of his sight.
"I want a clear way out of the house and all the cash you can get together. What! no more than that? I'd not be a lord to be kept so short. Find me some more."
Alured knew I should forgive him, and he took my key from my basket, unlocked the escritoire, and gave him my purse of household money, undid the shutters, and helped Perrault to squeeze himself through the little parlour window; and then, as he said, something came over him, and he just reached the sofa, and knew no more.
He did not tell all this about Hester before Mr. Halsted; only when Fulk, finding how shaken he was, had carried him upstairs, and we had taken him to his room, he asked anxiously whether anyone had heard Hester say that dreadful thing, and added, "Then if Mr. Perrault gets away no one will know—about her."
"Was that why you helped him?" we asked.
"Trevor told me to take care of her," he said; and then he told us of Perrault's arguments, but we ought not to have let him talk of them that night, for it brought back the shuddering and sobbing, and the horror seemed to come upon him, so that there was no soothing him or getting him calm till the doctor mixed an anodyne draught; and let it go as it would with Hester, I never left my boy till I had crooned him to sleep, as in the old times.
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