THE COST OF LIGHT

Artificial light is so superior to natural light in many respects that mankind has acquired the habit of retiring many hours after darkness has fallen, a result of which has brought forth the issue known as "daylight saving." Doubtless, daylight should be used whenever possible, but there are two sides to the question. In the first place, it costs something to bring daylight indoors. The architectural construction of windows and skylights increases the cost of daylight. Light-courts, by sacrificing valuable floor-area, add to the expense. The maintenance of windows and sky lights is an appreciable item. Considering these and other factors, it can be seen that daylight indoors is expensive; and as it is also undependable, a supplementary system of artificial lighting is generally necessary. In fact, it is easy to show in some cases that artificial lighting is cheaper than natural lighting.

The average middle-cla.s.s home is now lighted artificially for about $15.00 to $25.00 per year, with convenient light-sources which are available at all times. There is no item in the household budget which returns as much satisfaction, comfort, and happiness in proportion to its cost as artificial light. It is an artistic medium of great potentiality, and light in a narrow utilitarian sense is always a by-product of artistic lighting. The insignificant cost of modern lighting may be emphasized in many ways. The interest on the investment in a picture or a vase which cost $25.00 will usually cover the cost of operating any decorative lamp in the home. A great proportion of the investment in personal property in a home is chargeable to an attempt to beautify the surroundings. The interest on only a small portion of this investment will pay for artistic and utilitarian artificial lighting in the home. The cost of washing the windows of the average house may be as great as the cost of artificial lighting and is usually at least a large fraction of the latter. It would become monotonous to cite the various examples of the insignificant cost of artificial light and its high return to the user. The example of the home has been chosen because the reader may easily carry the a.n.a.lysis further. The industries where costs are a.n.a.lyzed are now looking upon adequate and proper lighting as an a.s.set which brings in profits by increasing production, by decreasing spoilage, and by decreasing the liability of accidents.

Inasmuch as daylight saving became an issue during the recent war and is likely to remain a matter of concern, its history is interesting. One of the outstanding differences between primitive and civilized beings is their hours of activities. The former automatically adjusted themselves to daylight, but as civilization advanced, the span of activities began to extend more and more beyond the coming of darkness. Finally in many activities the work-day was extended to twenty-four hours. There can be no insurmountable objection to working at night with a proper arrangement of the periods of work; in fact, the cost of living would be greatly increased if the overhead charges represented by such items as machinery and buildings were allowed to be carried by the decreased products of a shortened period of production. There cannot be any basic objection to artificial lighting, because most factories, for example, may be better illuminated by artificial than by natural light.

Of course, the lag of comfortable temperature behind daylight is responsible to some extent for a natural shifting of the ordinary working-day somewhat behind the sun. The chill of dawn tends to keep mankind in bed and the cheer of artificial light and the period of recreation in the evening tends to keep the civilized races out of bed.

There are powerful influences always at work and despite the desirable features of daylight-saving, mankind will always tend to lag. As years go by, doubtless it will be necessary to make the shift again and again.

It seems certain that throughout the centuries thoughtful persons have seen the difficulty of rousing man from his warm bed in the early morning and have recognized a simple solution in turning the hands of the clock ahead. Among the earliest advocates of daylight saving during modern times, when it became important enough to be considered as an economic issue, was Benjamin Franklin. In 1784 he wrote a masterful serio-comic essay ent.i.tled "An Economical Project" which was published in the _Journal_ of Paris. The article, which appeared in the form of a letter, began thus:

MESSIEURS: You often entertain us with accounts of new discoveries. Permit me to communicate to the public through your paper one that has lately been made by myself and which I conceive may be of great utility.

I was the other evening in a grand company where the new lamp of Messrs. Quinquet and Lange was introduced and much admired for its splendor; but a general inquiry was made whether the oil it consumed was not in exact proportion to the light it afforded, in which case there would be no saving in the use of it. No one present could satisfy us on that point, which all agreed ought to be known, it being a very desirable thing to lessen, if possible, the expense of lighting our apartments, when every other article of family expense was so much augmented. I was pleased to see this general concern for economy, for I love economy exceedingly.

I went home, and to bed, three or four hours after midnight, with my head full of the subject. An accidental sudden noise waked me about 6 in the morning, when I was surprised to find my room filled with light, and I imagined at first that a number of those lamps had been brought into it; but, rubbing my eyes, I perceived the light came in at the windows. I got up and looked out to see what might be the occasion of it, when I saw the sun just rising above the horizon, from whence he poured his rays plentifully into my chamber, my domestic having negligently omitted the preceding evening to close the shutters.

I looked at my watch, which goes very well, and found that it was but 6 o'clock; and, still thinking it something extraordinary that the sun should rise so early, I looked into the almanac, where I found it to be the hour given for his rising on that day. I looked forward, too, and found he was to rise still earlier every day till toward the end of June, and that at no time in the year he r.e.t.a.r.ded his rising so long as till 8 o'clock.

Your readers who, with me, have never seen any signs of sunshine before noon, and seldom regard the astronomical part of the almanac, will be as much astonished as I was when they hear of his rising so early, and especially when I a.s.sure them that he gives light as soon as he rises. I am convinced of this. I am certain of my fact. One cannot be more certain of any fact. I saw it with my own eyes. And, having repeated this observation the three following mornings, I found always precisely the same result.

He then continues in the same vein to show that learned persons did not believe him and to point out the difficulties which the pioneer encounters. He brought out the vital point by showing that if he had not been awakened so early he would have slept six hours longer by the light of the sun and in exchange he would have lived six hours the following night by candle-light. He then mustered "the little arithmetic" he was master of and made some serious computations. He a.s.sumed as the basis of his computations that a hundred thousand families lived in Paris and each used a half-pound of candles nightly. He showed that between March 20th and September 20th, 64,000,000 pounds of wax and tallow could be saved, which was equivalent to $18,000,000.

After these serious computations he amusingly proposed the means for enforcing the daylight saving. Obviously, it was necessary to arouse the sluggards and his proposals included the use of cannons and bells.

Besides, he proposed that each family be restricted to one pound of candles per week, that coaches would not be allowed to pa.s.s after sunset except those of physicians, etc., and that a tax be placed upon every window which had shutters. His closing paragraph was as follows:

For the great benefit of this discovery, thus freely communicated and bestowed by me on the public, I demand neither place, pension, exclusive privilege, nor any other regard whatever. I expect only to have the honor of it. And yet I know there are little, envious minds who will, as usual, deny me this and say that my invention was known to the ancients, and perhaps they may bring pa.s.sages out of the old books in proof of it. I will not dispute with these people that the ancients knew not the sun would rise at certain hours; they possibly had, as we have, almanacs that predicted it; but it does not follow thence that they knew he gave light as soon as he rose.

That is what I claim as my discovery. If the ancients knew it, it might have been long since forgotten; for it certainly was unknown to the moderns, at least to the Parisians, which to prove I need use but one plain simple argument. They are as well instructed, judicious and prudent a people as exist anywhere in the world, all professing, like myself, to be lovers of economy, and, for the many heavy taxes required from them by the necessities of the State have surely an abundant reason to be economical. I say it is impossible that so sensible a people, under such circ.u.mstances, should have lived so long by the smoky, unwholesome and enormously expensive light of candles, if they had really known that they might have had as much pure light of the sun for nothing.

Franklin's amusing letter had a serious aim, for in 1784 family expenses were much augmented and adequate lighting by means of candles was very costly in those days. However, conditions have changed enormously in the past hundred and thirty-five years. A great proportion of the population lives in the darker cities. The wheels of progress must be kept going continuously in order to curb the cost of living, which is constantly mounting higher owing to the addition of conveniences and luxuries.

Furthermore, the cost of light has so diminished that it is not only a minor factor at present but in many cases is actually paying dividends in commerce and industry. It is paying dividends of another kind in the social and educational aspects of the home, library, church, and art museum. Daylight saving has much to commend it, but the cost of daylight and the value of artificial light are important considerations.

The cost of fuels for lighting purposes cannot be thoroughly compared throughout a span of years without regard to the fluctuating purchasing power of money, which would be too involved for consideration here.

However, it is interesting to make a brief survey throughout the past century. From 1800 until 1845 whale-oil sold for about $.80 per gallon, but after this period it increased in value, owing apparently to its growing scarcity, until it reached a price of $1.75 per gallon in 1855.

Fortunately, petroleum was discovered about this time, so that the oil-lamp did not become a luxury. From 1800 to 1850 tallow-candles sold at approximately 20 cents a pound. There being six candles to the pound, and inasmuch as each candle burned about seven hours, the light from a candle cost about 1/2 cent per hour. From 1850 to 1875 tallow-candles sold at an average price of approximately 25 cents a pound. It may be interesting to know that a large match emits about as much light as a burning candle and a so-called safety match about one third as much.

A candle-hour is the total amount of light emitted by a standard candle in one hour, and candle-hours in any case are obtained by multiplying the candle-power of the source by the hours of burning. In a similar manner, lumens output multiplied by hours of operation give the lumen-hours. A standard candle may be considered to emit an amount of light approximately equal to 10 lumens. A wax-candle will emit about as much light as a sperm candle but will consume about 10 per cent. less weight of material. A tallow candle will emit about the same amount of light with a consumption about 50 per cent. greater. The tallow-candle has disappeared from use.

With the appearance of kerosene distilled from petroleum the camphene lamp came into use. The kerosene cost about 80 cents per gallon during the first few years of its introduction. The price of kerosene averaged about 55 cents a gallon between 1865 and 1875. During the next decade it dropped to about 22 cents a gallon and between 1885 and 1895 it sold as low as 13 cents.

Artificial gas in 1865 sold approximately at $2.50 per thousand cubic feet; between 1875 and 1885 at $2.00; between 1885 and 1895 at $1.50.

The combined effect of decreasing cost of fuel or electrical energy for light-sources and of the great improvements in light-production gave to the householder, for example, a constantly increasing amount of light for the same expenditure. For example, the family which a century ago spent two or three hours in the light of a single candle now enjoys many times more light in the same room for the same price. It is interesting to trace the influence of this greatly diminishing cost of light in the home. For the sake of simplicity the light of a candle will be retained as the unit and the cost of light for the home will be considered to remain approximately the same throughout the period to be considered. In fact, the amount of money that an average householder spends for lighting has remained fairly constant throughout the past century, but he has enjoyed a longer period of artificial light and a greater amount of light as the years advanced. The following is a table of approximate values which shows the lighting obtainable for $20.00 per year throughout the past century exclusive of electricity:

Hours Equivalent of Candle-hours Year per night light in candles per night per year 1800 3 5 15 5,500 1850 3 8 24 8,700 1860 3 11 33 12,000 1870 3 22 66 24,000 1880 3.5 36 126 46,000 1890 4 50 200 73,000 1900 5 154 770 280,000

It is seen from the foregoing that in a century the candle-equivalent obtainable for the same cost to the householder increased at least thirty times, while the hours during which this light is used have nearly doubled. In other words, in the nineteenth century the candle-hours obtainable for $20.00 per year increased about fifty times. Stated in another manner, the cost of light at the end of the century was about one fiftieth that of candle light at the beginning of the century. One authority in computing the expense of lighting to the householder in a large city of this country has stated that

coincident with an increase of 1700 per cent. in the amount of night lighting of an American family, in average circ.u.mstances, using gas for light, there has come a reduction in the cost of the year's lighting of 34 per cent. or approximately $7.50 per year; and that the cost of lighting per unit of light--the candle-hour--is now but 2.8 per cent. of what it was in the first half of the nineteenth century. No other necessity of household use has been so cheapened and improved during the last century.

In general, the light-user has taken advantage of the decrease by increasing the amount of light used and the period during which it is used. In this manner the greatly diminished cost of light has been a marked sociological and economic influence.

After Murdock made his first installation of gas-lighting in an industrial plant early in the nineteenth century, he published a comparison of the expense of operation with that of candle-lighting. He arrived at the costs of light equivalent to 1000 candle-hours as follows:

1000 candle-hours Gas-lighting at a rate of two hours per day $1.95 " " " " " three " " " 1.40 Candle-lighting 6.50

It is seen that the longer hours of burning reduce the cost of gas-lighting by reducing the percentage of overhead charges. There are no such factors in lighting by candles because the whole "installation"

is consumed. This is an early example of which an authentic record is available. At the present time a certain amount of light obtained for $1.00 with efficient tungsten filament lamps, costs $2.00 if obtained from kerosene flames and about $50.00 if obtained by burning candles.

In order to obtain the cost of an equivalent amount of light throughout the past century a great many factors must be considered. Obviously, the results obtained by various persons will differ owing to the unavoidable factor of judgment; however, the following list of approximate values will at least indicate the trend of the price of light throughout the century or more of rapid developments in light-production. A fair average of the retail values of fuels and of electrical energy and an average luminous efficiency of the light-sources involved have been used in making the computations. The figures apply particularly to this country.

TABLE SHOWING THE APPROXIMATE TOTAL COST OF 1000 CANDLE-HOURS FOR VARIOUS PERIODS

Per 1000 candle-hours 1800 to 1850, sperm-oil $2.40 tallow candle 5.00 1850 to 1865, kerosene 1.65 tallow candle 6.85 1865 to 1875, kerosene .75 tallow candle 6.25 gas, open-flame .90 1875 to 1885, kerosene .25 gas, open-flame .60 1885 to 1895, kerosene .15 gas, open-flame .40 1895 to 1915, gas mantle .07 carbon filament .38 metallized filament .28 tungsten filament (vacuum) .12 tungsten filament (gas-filled) .07

In these days the cost of living has claimed considerable attention and it is interesting to compare that of lighting. In the following table the price of food and of electric lighting are compared for twenty years preceding the recent war. The great disturbance due to the war is thereby eliminated from consideration, but it should be noted that since 1914 the price of food has greatly increased but that of electric lighting has not changed materially. The cost of each commodity is taken as one hundred units for the year 1894 but, of course, the actual cost of living for the householder is perhaps a hundred times greater than the cost of electric lighting.

Year Food Electric lighting 1894 100 100 1896 80 92 1898 92 90 1900 100 85 1902 113 77 1904 110 77 1906 115 57 1908 128 30 1910 138 28 1912 144 23 1914 145 17

One feature of electric lighting which puzzles the consumer and which gives the politicians an opportunity for crying "discrimination" and "injustice" at the public-service company is the great variation in rates. There is no discrimination or injustice when the householder, for example, must pay more for his lighting than a factory pays. The rates are not only affected by "demand" but by the period in which the demand comes. Residence lighting is chiefly confined to certain hours from 5 to 9 P. M. and there is a great "peak" of demand at this time. The central-stations must have equipment available for this short-time demand and much of the capacity of the equipment is unused during the remainder of the day. The factory which uses electricity throughout the day or night or both is helping to keep the central-station operating efficiently. The equipment necessary to supply electricity to the factory is operating long hours. Not only is this overhead charge much less for factories and many other consumers than for the householder, but the expense of accounting, of reading meters, etc., is about the same for all cla.s.ses of consumers. Therefore, this is an appreciable item on the bill of the small consumer.

Doubtless, the public does not realize that the enormous decrease in the cost of lighting during the past century is due largely to the fact that the lighting industry has grown large. Increased production is responsible for some of this decrease and science for much of it. The latter, having been called to the aid of the manufacturers, who are better able by virtue of their magnitude to spend time and resources upon scientific developments, has responded with many improvements which have increased the efficiency of light-production. Some figures of the Census Bureau may be of interest. These are given for 1914 in order that the abnormal conditions due to the recent war may be avoided. The figures pertaining to the manufacture of gas for sale which do not include private plants are as follows for the year 1914 for this country:

Number of establishments 1,284 Capital $1,252,421,584 Value of products (gas, c.o.ke, tar, etc.) $220,237,790 Cost of materials $76,779,288 Value added by manufacture $143,458,502 Value of gas $175,065,920 Coal used (tons) 6,116,672 c.o.ke used (tons) 964,851 Oil used (gallons) 715,418,623 Length of gas mains (miles) 58,727 Manufactured products sold Total gas (cubic feet) 203,639,260,000 Straight coal gas (cubic feet) 10,509,946,000 Carbureted water gas (cubic feet) 90,017,725,000 Mixed coal- and water-gas (cubic feet) 86,281,339,000 Oil gas (cubic feet) 16,512,274,000 Acetylene (cubic feet) 136,564,000 Other gas, chiefly gasolene (cubic feet) 181,412,000 c.o.ke (bushels) 114,091,753 Tar (gallons) 125,938,607 Ammonia liquors (gallons) 50,737,762 Ammonia, sulphate (pounds) 6,216,618

Of course, only a small fraction of the total gas manufactured is used for lighting.

According to the U. S. Geological Survey, the quant.i.ties of gas sold in this country in the year 1917 were as follows:

Coal-gas 42,927,728,000 cubic feet Water-gas 153,457,318,000 " "

Oil-gas 14,739,508,000 " "

Byproduct gas 131,026,575,000 " "

Natural gas 795,110,376,000 " "

In 1914 there were 38,705,496 barrels (each fifty gallons) of illuminating oils refined in this country and the value was $96,806,452.

About half of this quant.i.ty was exported. In 1914 the value of all candles manufactured in this country was about $2,000,000, which was about half that of the candles manufactured in 1909 and in 1904. In 1914 the value of the matches manufactured in this country was $12,556,000.

This has increased steadily from $429,000 in 1849. In 1914 the gla.s.s industries in this country made 7,000,000 lamps, 70,000,000 chimneys, 16,300,000 lantern globes, 24,000,000 shades, globes, and other gas goods. Many millions of other lighting accessories were made, but unfortunately they are not cla.s.sified.

Some figures pertaining to public electric light and power stations of the United States for the years 1907 and 1917 are as follows:

1917 1907 Number of establishments 6,541 4,714 Commercial 4,224 3,462 Munic.i.p.al 2,317 1,562 Income $526,886,408 $175,642,338 Total horse-power of plants 12,857,998 4,098,188 Steam engines 8,389,389 2,693,273 Internal combustion engines 217,186 55,828 Water-wheels 4,251,423 1,349,087 Kilowatt capacity of generators 9,001,872 2,709,225 Output in millions of kilowatt-hours 25,438 5,863 Motors served (horse-power) 9,216,323 1,649,026 Electric-arc street-lamps served 256,838 ....

Electric-filament street-lamps served 1,389,382 ....

In general, there is a large increase in the various items during the decade represented. The output of the central stations doubled in the five years from 1907 to 1912, and doubled again in the next five years from 1912 to 1917. Street lamps were not reported in 1907, but in 1912 there were 348,643 arc-lamps served by the public companies. The number of arc-lamps decreased to 256,838 in 1917. On the other hand, there were 681,957 electric filament street lamps served in 1912, which doubled in number to 1,389,382 in 1917. The cost of construction and equipment of these central stations totaled more than $3,000,000,000 in 1917.

Although there is no immediate prospect of the failure of the coal and oil supplies, exhaustion is surely approaching. And as the supplies of fuel for the production of gas and electricity diminish, the cost of lighting may advance. The total amount of oil available in the known oil-fields of this country at the present time has been estimated by various experts between 5,000,000,000 and 20,000,000,000 barrels, the best estimate being about 7,000,000,000. The annual consumption is now about 400,000,000 barrels. These figures do not take into account the oil which may be distilled from the rich shale deposits. Apparently this source will yield a hundred billion barrels of oil. In a similar manner the coal-supply is diminishing and the consumption is increasing. In 1918 more than a half-billion tons of coal were shipped from the mines.

The production of natural gas perhaps has reached its peak, and, owing to its relation to the coal and oil deposits, its supply is limited.