The commercial uses for ice are increasing, and the ice-manufacturing industry is especially interested in the development of equipment which will utilize ice to cool homes and commercial buildings.

The manufacture of ice boxes, on the other hand, has dropped as precipitately as the production of electric refrigerators has risen. Sales of ice boxes in 1930 were less than half a million, according to reports, as compared with nearly 1,300,000 in 1924 and in 1926. Each succeeding year has shown further declines; but although unit sales of ice boxes have been declining, two or three makes of the "de luxe" variety have been enjoying good volume. It is the market for cheap ice boxes-which formerly comprised the vast bulk of production-which has contracted.

A comparison of the sales of electric refrigerators since the beginning of that industry in 1920 with the sales of ice boxes over the same period clearly demonstrates that even if the same number of man-hours were necessary to produce each, no technological unemployment could have resulted from the introduction of this development.

1 Refrigeration and air-conditioning market data, Business News Publishing Co., Detroit, Mich.

The introduction of electric refrigeration has unquestionably changed the buying habits of many people. Perishable foodstuffs can be kept for longer periods even in tropical climates, and larger quantities may consequently be purchased (usually at a saving) by small families. Apartment house owners have been quick to appreciate the fact that an installed electric refrigerator adds to the appeal (and in many cases the rent) of their units.

Electric refrigeration has greatly contributed to the ease with which various medicinal products and serums may be preserved; and has made the preservation of perishable foodstuffs possible, even in remote areas where commercial ice was never available. In addition to the domestic electric refrigerator, we also find developments in the commercial field. One of the largest and most profitable markets for commercial refrigeration is the dairy industry. Low-tem

perature show cases for the display of perishable foods will keep those foods almost indefinitely, and we are now seeing the engineers of the electrical-goods industry assisting in the solution of the problem of providing refrigerated trucks. This demand for satisfactory mechanically refrigerated trucks has arisen from dairies and ice-cream manufacturers, and from producers of quick-frozen foods.

Ultra-violet and Infra-red Rays.-Strange as it may seem, the part of the sun's rays which are most beneficial to our health are completely invisible. Our eyes are built to register only certain parts of the sun's rays, just as a radio is capable of receiving waves of only certain lengths. There can be no disagreement with the idea that sunlight is essential to our health, but how many people today realize that the rays which really contribute most to our health do not pass through ordinary window glass? Because these health-giving rays cannot be seen and because so much time is spent indoors, it is becoming more and more important to give attention to providing these rays artificially.

There are two distinct types of rays produced by sun-ray lamps. One is the ultra-violet ray and the other, the infra-red ray.

The ultra-violet ray contains very little heat and reacts on the blood stream of the body, increasing the supply of the valuable vitamin D, and producing the well-known effect of sunburn technically called "erythema." This ray is of great benefit in preventing and curing rickets and in building up sound bones and teeth, improving general health and building resistance to disease.

The other type of invisible ray produced is called the infra-red ray. This is a heat ray which penetrates beneath the surface of the skin and is helpful in relieving pain, relaxing spasm, and promoting circulation.

While artificial sunlight equipment has been used by physicians for a great many years in their treatment of disease, it is only within recent years that lamps which are safe and convenient for the home have been available. The first equipment perfected for home use was very similar to that used by physicians. These devices were large and rather cumbersome units which produced a very high percentage of the valuable invisible rays-such as would reach us from the sun if it were not for the clouds, dust, and smoke in the air, and for the ordinary window glass which filters out many of the beneficial rays.

The advance in the art of producing artificial sunlight has been so rapid during the past few years it is entirely possible that, within the next decade, the usual illumination in the home will include sufficient ultraviolet to afford most of the healthful benefits of sun

light itself. Already these units are available so that midsummer sunlight may be had in any home and the benefits enjoyed while reading or bathing, or while the children are playing regardless of the season or the weather.

And so it can be seen that some of the technological developments in the electrical-goods industries are enabling man to control his climatic conditions indoors. The effects of this ability upon daily life will be further discussed in subsequent sections of this paper.

Vision

Lighting.-Thomas A. Edison produced the first commercially successful incandescent electric lamp in 1879. This was the beginning of the incandescentlamp industry, but its growth depended primarily upon the development of economical sources of current. Edison realized that, and it was largely through his efforts that the first central station for the supplying of electric current was constructed in New York in 1882. The carbon-filament-lamp industry grew with the central station industry until nearly 50,000,000 carbonfilament lamps were sold in the United States during 1906. The rapid growth of the industry since that time is directly traceable to technological improvements and inventions which are making this source of illumination constantly more economical and efficient.

1 Does not include miniature, automobile, or Christmas-tree lamps.

It seems altogether likely that such progress will continue rapidly, since we are still getting as light from the most efficient, big tungsten lamps only 15.5 percent of the current used, which means 2.2 percent at best from the coal burned. The cold light of the firefly is 96.5 percent light and only 3.5 percent heat; and we are beginning to understand and are experimentally copying his secret. Already great strides forward in the improvement of the efficiency of artificial illumination are being made in vapor lamps; for example-the present commercially available 400-watt high-intensity mercury vapor lamp produces 40 lumens per watt. Unfortunately, this mercury lamp gives an unpleasant bluish glow. Likewise, sodium vapor gives a yellowish glow, which chromatic properties make these lamps at present unacceptable for general use. It is entirely reasonable to assume that in the near future we may be able to closely duplicate the sunlight spectrum by a combination of those or other vapors in a single highly

efficient lamp. However, some day the direct use of electricity for illumination may be as obsolete as the use of whale oil now is. This perhaps may be accomplished through the economical manufacture of synthetic luciferin which when oxidized by the air gives cold, firefly's light, almost 100 percent efficient, diffused, not glaring, and involving no fire risk, wiring, or electricity. There may be luminescent paints which may store up sunlight during the day to glow with various colors during the night.

Much research is being carried on in the field of illumination to determine accurately the lighting requirements for the best performance of various tasks. The results of this work will be manifested in the prolongation of better eyesight in future generations. Already it is not uncommon to find schools equipped with the ever alert photoelectric cell to switch on classroom lights when the illumination from outdoors falls below a predetermined point. The lightmeter, which provides a convenient method of reading the existing illumination in foot-candles has just recently been supplemented by the visibility meter, which provides an equally convenient means of determining the footcandles recommended for the performance of a given task. The research in this field has really only begun, but indications are that we will eventually be able to discover means not only of conserving our very valuable eyesight but also will be permitted to perform our daily work, whatever it may consist of, more efficiently and comfortably and leave those tasks less tired and less nervous.

Great progress has been made in the field of outdoor lighting, flood lighting for the beautification of nature and man-made buildings and objects, lighting which makes possible outdoor sports events at night, the landing of aircraft in darkness, the reduction of crime through better street lighting, and advertising by electric signs using both incandescent lamps and luminous tubing containing neon and other gases. Much work remains to be done in the field of stimulating plant growth by the use of artificial lighting.

Highway Lighting.-One of the applications of outdoor lighting which offers the greatest possibilities is the lighting of our highways.

Modern automobile headlights are designed for use with lamps having two beams; one of which is a raised beam for use when driving on the open road, and the other is a depressed beam for use in approaching another car. When properly focused and adjusted and with lamps and reflectors in perfect condition, they provide adequate visibility on straight, level, nonspecular roads. However, statistics compiled by the Travelers Insurance Co., based on inspections of thousands of cars in various cities and States, reveal that

in 63 percent of the cases headlight adjustments or lamp replacements are required.

Even more important for the safety of driver and pedestrian alike, especially after dark, are the extent and nature of highway lighting. Increased speeds of driving have made even more imperative dependable visibility. Proof of the importance of adequate illumination in the prevention of night accidents is available in numerous reports covering most parts of the country. The National Safety Council obtained the figures used in the following chart (see fig. 46) from the commissioners of motor vehicles in the States of New Jersey, Oregon, New York, North Carolina, and Pennsylvania. These States have almost one-quarter of the population, automobile registration, and gasoline consumption in the United States. (One curve shows the total number of fatalities for the summer months of May, June, and July. The other shows similar data for November, December, and January.)

It is observed that the two curves are approximately the same, except for the period 5 to 8 p. m. Why should there be such an abrupt rise in accidents after 5 p. m. in winter? Winter traffic is known to be less than that in summer. This accounts for the fact that during the daylight hours there are fewer winter accidents than in summer (although the effect of reduced traffic in winter is partially offset by that of slippery road surfaces). However, in the hours of 5 to 8 p. m., which are hours of daylight in summer and darkness in winter, the winter accidents are 58 percent higher than the summer accidents. The only possible reason for this increase is the lack of illumination in winter. In the hours of daylight in both summer and winter, the winter accidents average 76.4 percent of the summer accidents. Based on this percentage, the expected winter accidents during the period 5 to 8 p. m. are as shown by the broken line on the chart, and the shaded area represents the amount chargeable to lack of illumination. This shows that a reduction of 47 percent in night accidents resulting in fatalities should be possible if illumination equivalent (for purposes of seeing) to daylight conditions should be provided on the highways. Considering all the limitations of artificial lighting, it seems reasonable to believe that at least 35 percent of the night fatal accidents should be prevented by the provision of adequate highway lighting.

In 1933, R. E. Simpson studied the day and night fatality rate for 60 cities in comparison with the accident exposure. He considered the traffic unit (a measure of exposure) to consist of either one pedestrian crossing the street or one automobile traveling 1 mile. He found that the average day fatality rate per M. T. U. (million traffic units) on streets carrying over

8778°-37--22

While the extension of highway lighting may be justified on the basis of cold dollars-and-cents economics, based on anticipated reduction of night accidents, numerous other social effects may be expected. Some of these are the following:

(a) Reduction in Highway Crime.-It has been shown time and again that in cities the installation or improvement of street-lighting facilities invariably led to a reduction in street crime. Crooks work in the dark. Similar results may follow the lighting of the highways.

(b) More Efficient Utilization of the Highways.— Estimates show that about 80 percent of the traffic is in the daytime and 20 percent at night. This means that the tremendous investment in our highway system is being wasted during the hours of darkness. People try to avoid night driving because they realize that

the probability of their being killed or killing someone else while driving at night is many times as great as it is in the daytime. Lighting the highway will stimulate more night driving (particularly of trucks) and thereby relieve the daytime congestion.

(c) Increased Comfort and Enjoyment of Night Driving.-The strain of trying to see by inadequate illumination is terrific as experiments by Dr. Matthew Luckiesh have shown. It has been found that adequate illumination makes seeing easy, the driver relaxes, and the trip is changed from a nightmare to a pleasant experience.

(d) Stimulus to Progress in Rural Electrification.The extensive development of highway lighting would assist greatly in the promotion of rural electrification. The poles specified in the preparation of cost estimates should be suitable for carrying a power-distribution circuit as well as the lighting system. The chief obstacle to the development of rural electrification will, therefore, be greatly reduced.

The present trend toward extension of highway lighting may be expected to receive added stimulus especially through the use of the recently invented brighter sodium lamp, the cheapening of electricity, and the pressure for rural electrification.

Sound

Public Address Systems. In the field of sound there are to be found many developments of the laboratories of the electrical-goods industries. Foremost among these developments are the telephone, telegraph, and radio which are discussed in the chapter on communications. However, there are other applications in the field of sound which are also important; for example— the public-address system, which enables one man to speak with the voice of a thousand men, has unquestionably had its subtle social implications which are often overlooked. Formerly our men in public life. were almost invariably endowed with leather lungs and a stentorian voice but now even the mild voiced little man can make himself heard to an assembly of hundreds of thousands, and by radio to millions.

When President Lincoln delivered his Gettysburg address, perhaps but a few hundred fortunate souls in the great assembly were actually able to hear his famous words; but when President Roosevelt delivered his inaugural addresses, all of the anxious thousands grouped about the Capitol (not to mention the additional millions of radio listeners) were able to hear his every syllable clearly and distinctly.

The ability of the public-address system to amplify the human voice is a tremendous factor in modern life. The control of mob action, particularly in times of emergency, means the saving of many lives, and the

public-address system provides a means to this end, which has already demonstrated its effectiveness many times. Many Coast Guard cutters are now equipped with this device which greatly facilitates their rescue work by permitting the human voice to be heard clearly even above the roar of the sea and wind.

Cultural life has been enriched by the ability of the public-address system to carry the voice of lecturers distinctly to everyone in the assembly. Research engineers have adapted these same principles of sound amplification in the development of equipment which enables many deaf persons to hear, thus rehabilitating these unfortunate persons by permitting them to pursue their lives less hampered by their disability.

Electric Organ.-A recent achievement of our electrical research laboratories is the electric organ which is built to conform to established pipe-organ standards and, while it requires pipe-organ technique in the playing, has no pipes, reeds, or other vibrating parts. The instrument can never get out of tune and occupies about the same space as an upright piano, thus making it available to lovers of this type of music who live in small homes or apartments. Although this instrument may produce duplicate diapason and flute pipe tones, or orchestral strings and reeds, yet the organ itself contains no physical counterpart of any of these things. The initial cost is low relative to that of a pipe organ-the maintenance cost is that of a radio receiving set and the operating cost is less than 1 cent per hour. Many churches, schools, and private individuals are now using and enjoying this technological development. Perhaps this may mark the beginning of the mechanization of many of our other musical instruments. The least that can be said is that it has already revived interest to a very marked degree in hitherto expensive, and one might almost say declining, branch of musical art.

Burglar-Alarm Systems.-In nearly every type of our modern burglar-alarm system will be found a development of the laboratories of the electrical-goods industry. These systems usually employ the photoelectric cell actuated by either infra-red or visible light, direct closing of a circuit when a window or door is opened, or the magnetic field or capacitance effect which permit the detection of weapons or other large pieces of metal even when concealed. Electric burglar alarms may summon the police, ring bells, turn on floodlights, photograph the intruder, discharge tear or other gases; but the one duty which any of the systems performs is to reduce crime by providing a greater measure of safety for banks, factories, offices, homes-by making it increasingly difficult to commit a crime without immediate detection. Even after the crime has been detected and the criminal apprehended

these same alarm systems are employed in prisons to prevent his escape. Applied electricity has contributed materially to society in this respect by providing protection which otherwise would be impossible.

Productive Activities

Other Devices.-Other applications in the field of sound include "talking books" for the blind, electric bells and chimes for our homes, and the electrically recorded and reproduced records for our amusement.

Motors.-Probably no other electrical tool so symbolizes the idea of technological development in the electrical-goods industry as the electric motor. Yet one of the many things which the people of 50 years ago did not know and which has been in a large measure responsible for amazing industrial advance in all fields was the fact that the electric motor would bring cheap and efficient power to factories, revolutionize industrial processes, and perform virtually all the mechanical operations of whole industries. Today, 35,000,000 horsepower in electric motors turn the wheels of industry. And to industry this increasing efficiency meant better motors, more types of motors, lighter motors, and less expensive motors.

In 1900, one manufacturer made five types of motors, and every one was custom built. Today, this same manufacturer with stocks in 29 warehouses, can supply immediately a motor for practically any appli

cation.

In 1900, a 5-horsepower polyphase motor weighed 716 pounds. Today, it weighs only 191 pounds, a reduction of 73 percent.

In 1900, that 5-horsepower motor occupied 19,700 cubic inches. Today, it takes up only 4,380, a reduction of 77 percent.

Today, the user without discount can buy three and one-half 3-horsepower motors for the same number of dollars that he would have had to pay for one 3-horsepower motor in 1900.

Of all the tools that ever came into the hand of man, electric motors and control have been among the greatest. Touching a button, the modern American. workman sees electricity, through a motor, multiply his own strength a thousandfold and increase his producing ability in countless ways. By the improvement of this industrial efficiency it is possible to produce more things for more people at less cost, both the things which make for a more abundant life and things which assist us in the performance of our daily work.

Photoelectric Cells.-Silently into our lives is creeping a new technological brain-child whose ultimate social import cannot now be estimated. It is the photoelectric cell or electric eye as it is popularly known.

General Electric Co.

A few of the functions which this apparatus is capable of performing:

A list of photo-cell applications

Industrial: Reversing rolls in steel mill.

Removal of soaking-pit

covers.

chines.

Safety protection of machines.

Detection of flaws in

products.

Alarm for water hardness. Analysis of card records. Fire alarms, smoke alarms.

Paper-inaking machine paper-break detection. Automatic weighing of

batches.

Chemical process control. Leveling elevators. Inspect

storage battery caps for vent holes. Sorting electrical resist

ances.

Controlling thickness of enamel on wires. Rejection of nonsharp razor blades. Food and chemical processes: Controlling levels of contents of tanks and bins. Drinking fountain control.

Food and chemical processContinued.

Cold-room door operation. Opening doors for animals (dairy, stables, etc.).

Tooth-paste filling machines.

man.

Parking lights on autos, automatically lighted at

dusk.

Excerpted from a list of compiled by Electromics McGraw-Hill, New York (October 1933).