upon the printing of the future and corresponding influences upon social changes. Of such is the present tendency of paper manufacturers to produce a sheet which has the same qualities for ink reception on both sides of the sheet instead of possessing different printability on the opposite sides-wire side and felt side— as at present. In electrotyping reduplication, chemistry is playing the role of speeding up the electrodeposition of the copper shell as well as improving its grain structure by the addition of phenolsulphonic acid to the copper sulphate plating baths and by other

means.

In molding plates for reduplication, a new wax mold is being developed to be laid upon a soft metal base with the purpose of displacing the ozokerite wax mold or the lead-molding process in the future.

There is a trend toward replacing metal printing plates in part by rubber-composition printing plates which in some cases have a greater facility for transferring inks (especially water-color printing inks) to the paper than do metal surfaces. Similar effects. have been obtained by the electrodeposition of rubber from solutions upon the surface of metal plates and types.

The printing of tabulating cards for use in special accounting machines is a recent trend that should be especially noted. It is rapidly becoming possible by means of these perforated cards and the machines which sort them, to gather vast amounts of information of a statistical nature with a minimum of time and effort. Business is increasingly using this means for its analytical studies of financial conditions, and hospitals benefit by the ease of clinical classification and study of cases. Statistical studies of every sort, in every channel of human activity, may be made by this simple means. The printing of the punch cards requires great accuracy of register in order that they may function properly in the counting machines, and the paper from which they are cut must be of particular grade. A great many numbers may be printed in columns for perforation on a single card, and by combination of these numbers in a code system the uses to which they may be put in the gathering of information are practically limitless.

By special photographic methods, half-tone printing plates may now be made directly upon celluloid film, the celluloid serving as the printing surface in place of metal and the process of acid etching being entirely eliminated. These celluloid printing plates may be used directly on the presses or may be reduplicated by molding for electrotype or stereotype reproduction. They will function chiefly in the field of newsprint.

The substitution of a thin silver film on the electrotype wax mold in place of graphite powder to give

8778°-37-17

the surface electrical conductivity may be effective in producing a better quality of printing plates.

The electroplating of harder metals, such as nickel or chromium, upon the surface of zinc-grained plates as used in offset printing and upon other metal printing surfaces is another recent technological trend toward obtaining a larger number of impressions from a single set of plates.

The substitution of synthetic resins for the greatly variable resin products obtained from natural sources and widely employed in the graphic arts is another step forward in the line of printing progress. Synthetic resins are susceptible of accurate technical control and duplication. Their substitution for dragon's blood and use in printing inks and press rollers are already on the way and will do much toward eliminating for the printer many troubles which result from the inconstancy of the materials he is forced to depend

upon.

There are many other developments daily brought to light through scientific research as applied to printing which in large or small ways will unquestionably in their total effects exercise great influence upon the art of printing within the next few decades.

The function of the press as a means of mass communication through the channel of sight has no rival save the appeal by sound to the ear of the radio listener. To meet the public demand for news of current world events, quickly available and widely distributed, the printing processes have been developed through research and invention to a very high degree of efficiency. An example of this is shown in the recent press publication of pictures illustrating the events of the Olympic games in Germany and the civil strife at present raging in Spain, transmitted by radio waves simultaneously with the reports of the events themselves.

The potentiality of printing for both good and evil as an instrument of social influence, education, and the determination of public policies is almost without limitation. Like many other human inventions it derives its character from the motivation of human actions and the uses to which it is subjected. No prophecy could here be ventured as to the future course of this inherent power of printing.

In the midst of the complex social order representing the present status of civilization it must be left to the capacities of the imagination to delineate a picture of the social and economic changes which may occur in the generations immediately succeeding our own as a result of these trends in printing. Certainly the development of the mechanical means of world-wide communication and the exchange of knowledge is rapidly advancing and extends great opportunity for social intercourse among all peoples.

The great variety and multiplicity of patents which are now being issued in the field of printing and photography are an augury of this progress. It would not be possible within the scope of this article to record these ever-occurring inventions and evaluate their possible influences upon the future of printing as one of the great channels of communication. We have therefore only touched upon a few illustrative examples.

It would not be fitting to conclude without paying tribute to the powerful agency which is bringing about these remarkable changes in a long-established and once very conservative trade. Scientific research, applying the principles of chemistry and physics to the solution of problems of cause and effect, is rapidly opening the doors once locked against progress by a jealous secrecy formerly maintained throughout the craft. The slogan of the modern printer craftsman is "Share your knowledge", and this newborn spirit is carrying forward the ancient art by leaps and bounds.

Paper manufacturers, machine builders, ink makers, and process printers are now in cooperative contest to improve the quality, increase production, and reduce the costs of printing by scientific methods of procedure and control. This awakening to the value of scientific research in the printing industry is not local to the United States but is world-wide in scope. In some countries a national interest is being shown in organizing groups for investigational research.

The investment of all cooperative investigation applied to printing and photography as related to printing must return in the future in the form of great dividends to the progress of this venerable art.

Acknowledgment

In connection with the preparation of this article the author desires to make acknowledgment to Dr. George C. Havenner, Liaison Officer, and Mr. Ernest W. Spencer, Assistant Technical Director, of the Government Printing Office, for their assistance rendered in research and editorial work.

I. THE

America's Power-Producing Capacity

The United States of America leads the entire world in the amount of power available and used. The major users of mechanical power are manufacturing industries, agriculture, mines and quarries, transportation systems, and homes. The power used by manufacturing industries, agriculture, mines and quarries is either manufactured in isolated plants or is purchased from a public utility which may be under private or public ownership.

Transportation systems, which include motor vehicles, railroads, marine propulsion (steamships and motor ships), and airplanes usually carry their own power generating equipment; an exception to this are electric railways, busses with trolleys, and electric street cars which operate on current supplied from a central station at some convenient point.

Domestic power users, including urban and to an increasing extent also rural customers, depend for their power supply upon a public utility central

POWER

The installed electric generator capacity in this country of nearly 33.5 million kilowatts may be compared with 12.8 million in Germany, 10.1 in France, 7.25 in Great Britain, 6.1 in Canada, 5.47 in Soviet Russia, and 5.3 in Japan, and 4.55 million kilowatts in Italy. On the per-capita basis, the installed generator capacity of the United States is 0.27 kilowatts as compared with 0.19 in Germany, 0.24 in France, 0.16 in Great Britain, 0.59 in Canada, 0.033 in Union of Soviet Socialist Republics, 0.077 in Japan, and 0.11 in Italy.

Of the installed generating capacity in electric central stations, fuel prime movers, i. e., plants utilizing fuel, represented as of December 31, 1935,2 a total of 24,488,400 kilowatts, or 73.2 percent and hydroelectric plants, 8,958,000 kilowatts, or 26.8 percent. Of the fuel prime movers in electric-power stations, steam plants represented 98 percent, and internal-combustion engines made up 2 percent. About one-half million kilowatts installed capacity in Diesel engines was reported in electric-generating stations at the end of 1934. More than half of the Diesel capacity, or 280,000 kilowatts was in municipal power plants. The trend in the sources of power used in electric central stations is shown by table 12, compiled from data published by the National Electric Light Association in 1931 and by the Edison Electric Institute in 1935.

TABLE 12.-Horsepower of installed capacity in electricgenerating stations

Locomotives-Marine__

Total horsepower_.

3,500,000

1902.

1912.

88, 000, 000

1922.

The Electric Central Station Industry.-At the end of 1935 this industry had an installed generating capacity of 33,446,400 kilowatts, which is equal to 44,670,000 horsepower. Of this capacity public utilities under private control had an installed capacity of about 94.5 percent of the total; those under public control about 5.5 percent of the total.

1 Section I of this chapter, The Production of Power, was contributed by A. A. Potter, dean of engineering, Purdue University; president, American Engineering Council. M. M. Samuels, electrical engineer, Federal Power Commission, prepared the second section, Transmission and Distribution of Electrical Energy.

44, 670,000

The Federal Power Commission has reported for the year 1935 the capacity of publicly owned hydroelectric plants as 853,000 kilowatts. Of this total 455,000 is represented in municipal plants, 38,000 in the Bureau of Reclamation, and 360,000 kilowatts in generating capacity as owned and operated by State and Federal Governments.

2 Edison Electric Institute Bulletin, February 1936 (estimates by the Federal Power Commission for 1935 are 34,446,400 kilowatts distributed in the following manner: Private, 31,578,941; municipal, 1,973,446; and Federal and State Government, 467,949 kilowatis). One kilowatt 1.33 horsepower.

In the national power survey Interim Report of 1935, published by the Federal Power Commission, the total production of electricity by the major utility systems of the country is given for the year 1933 as 76,882 million kilowatt-hours, of which 59 percent was generated by steam power, 41 percent by water power, and only 0.09 percent by internal-combustion engines, including Diesel plants. As of December 31, 1935 the Edison Electric Institute in its bulletin of February 1936, gives the kilowatt-hours generated for the year 1935 as 92,328.3 million kilowatt-hours, of which 59.5 percent was generated by fuel-power plants and 39.5 percent by waterpower.

The growth of the so-called electric light and power industry is indicated by comparing the output of 92 billion kilowatt-hours in 1935 with 80 billion in 1927, 25.5 billion in 1917, 11.5 billion in 1912, 6 billion in 1907, and only about 2.33 billion kilowatt-hours in 1902. Since 1882 and until 1929 the output of electric central stations has practically doubled every 5.5 years. The present electric output in this country of over 92 billion kilowatt-hours should be compared with 31 billion in Germany, 20.7 billion in Great Britain, 20.5 billion in Soviet Russia, 19.3 billion in Canada, 18.16 billion in Japan, 15.3 billion in France, and 11.9 billion kilowatt-hours in Italy. These figures of electric output on the per capita basis are 678 for the United States, 398 for Germany, 405 for Great Britain, 97 for Union of Soviet Socialist Republics, 1,629 for Canada, 269 for Japan, 356 for France, and 265 kilowatt-hours for Italy.

3

The revenue of the electric utility industry from sale of energy to ultimate consumers has grown in this country from 84 million dollars in 1902, to 282 million in 1912, to 1,029 million in 1917, to 1,661 million in 1927, to 1,991 million in 1930, and to 1,921 million dollars in 1935. At the same time the capital invested 5 in this industry has increased from 505 million in 1902, to 2,176 million dollars in 1912, to 4,456 million in 1922, to 11,850 million in 1930, and to 13,100 million in 1935, the figure for 1935 being the estimate of the Federal Power Commission.

The Edison Electric Institute in its statistical bulletin No. 2 (table XX), dated April 1935, gives the total investment of electric generating systems as $12,664,376,952 for 1934, of which 95.75 percent was invested in private electric utilities and 4.25 percent in municipal plants.

The electric central station industry which had its beginning in September 1882, has developed during the past 54 years so that it ranks fifth among all indus

3 Compiled from figures published in the Electrical World and by the Edison Electric Institute.

Supplied by the Federal Power Commission.
Statistical supplement, N. E. L. A., 1931.

tries of the country in the amount of money invested and thirteenth in point of number of employees and the value of its product. The following data about this industry are significant:

In the 30-year period from 1902 to 1932 the Federal Power Commission reports that the value of the electric central station industry's plant and equipment increased 25 times; its income from electric service, 23 times; its generating capacity, 29 times; its output, 32 times; and its employees, 8 times.

At the beginning of 1935 the electric utility industry consisted of approximately 1,620 privately owned operating companies and 1,930 municipal systems.

The average selling price of electricity in cents per kilowatt-hours for household use has been reduced from 25 in 1882, to 16.2 in 1902, to 9.1 in 1912, to 7.38 in 1922, to 5.58 in 1932, and to 5.03 in 1935. The United States Bureau of Labor statistics, with the 1913 index as 100, gives the index for 1882 as 287, for 1902 as 186, for 1912 as 104.6, for 1922 as 85, for 1932 as 63.1, and for 1935 as 57.8.

The average cost per kilowatt-hour for large consumers of power 5 has decreased from 1.69 cents in 1921 to 1.29 cents in 1935. The wholesale cost of power delivered to market centers has been estimated by F. F. Fowle, consulting engineer of Chicago to be 1.25 cents per kilowatt-hour and the cost of distribution 3.05 cents, making the average cost 4.3 cents per kilowatt-hour.

5

The use of electricity in kilowatt-hours per annum by domestic customers has been increased from 264 in 1913, to 359 in 1922, to 548 in 1930, and to 673 in 1935. At the same time the average annual bill paid by domestic customers has changed from $22.97 in 1913 to $26.50 in 1922, to $33.04 in 1930, and $33.85 in 1935. Thus the use from 1913 to 1935 has increased over two and a half times while the cost for the larger amount was only 47 percent more in 1935 than it was for the smaller amount in 1913.

The number of wired homes in this country has increased from about 3 million in 1912 to 1014 million in 1922 to 2011⁄2 million in 1930, and to about 2114 million in 1935.

The electrified farms of the United States, served by central stations, increased from 177,561 in 1923 to 649.919 in 1930 and to 788,795 in 1935. In addition to these figures 250,000 farms are being served by individual electric-lighting plants.

The number of customers served by the electric central station industry, has increased from 583,000 in 1902 to 3,837,518 in 1912, to 12,709,868 in 1922, to 24.

Statistical supplement, N. E. L. A., 1931.

Statistical bulletin, Edison Electric Institute, April 1935. Supplied by the Federal Power Commission. Source: Edison Electric Institute bulletins.

664,000 in 1930, and to 25,370,966 as of December 31, 1935.

The per capita use of electricty has increased from 30 kilowatt-hours per annum in 1902 to 734 in 1935, or more than 15 times as fast as the population growth of this country. (The maximum per capita use was 762 for the year 1929.)

Industrial Power Plants.-These in 1934 had a generating capacity of about 15,000,000 kilowatts, which is equal to 20,133,000 horsepower. The generating capacity of industrial power plants has increased from 3,411,000 horsepower in 1880, to 16,803,000 in 1910, to 19,900,000 in 1920, and to about 20,000,000 in 1935.5

The census figures for 1929 gave a total of 42,544,358 horsepower for 192,004 industrial establishments, excluding generators.

The trend in different types of power equipment in industrial power plants is shown, in horsepower, in

The above table shows that purchased power which represented in 1899 only 1.8 percent of the total power used by industry had increased in 1919 to nearly onethird and in 1927 to nearly one-half. No accurate data could be secured for 1935 but the figures for that year, it is believed, do not differ greatly from those for 1927. The rapid electrification of industry is indicated by the increase in the total horsepower of electric motors used in factories from 492,936 in 1899, to 4,817,140 in 1909, to 16,253,702 in 1919 and to 30,361,106 in 1927. The percent of electrified tools and machines of American industry has increased from 4 in 1899, to 23 in 1909, to 53 in 1919, and to 75 percent in 1927. Electric Railway Plants.-Those not supplied with current by the electric-light and power plants had an installed capacity during 1935 of about 2,500,000 horsepower. Street railways and rapid-transit lines during 1934 generated 2,276 million of kilowatt-hours in their own plants and purchased during the same year 5,005 million kilowatt-hours, the purchased power representing 68.7 percent of the total.

Statistical supplement, N. E. L. A., 1931.

Frank F. Fowle before Midwest Power Engineering Conference based the figure of 15,000,000 kilowatts for 1934 upon census statistics for 1929 with minor allowance for growth.

"Data supplied by the Federal Power Commission.

Mines and Quarries.10-The installed or available capacity of electric motors in mines and quarries is at present about 5,000,000 horsepower, having increased from 221,159 horsepower in 1909. However, the prime-mover capacity has decreased from 3,384,548 horsepower in 1909 to 2,743,025 horsepower in 1929. In 1929 mines and quarries purchased 5,382 million kilowatt-hours and generated 2,081 million.

Agricultural Prime Movers.-In Bulletin 157 of the United States Department of Agriculture, dated April 1933, the total horsepower used in agriculture is given as 70,501,795. This estimate includes 25,000 steam engines averaging 40 horsepower and 1,000,000 windmills averaging 0.33 horsepower each; also 18,161,386 horses and mules at 0.95 horsepower each; 920,021 tractors at 23.9 horsepower each; and 1,131,108 gasoline engines at 2.68 horsepower each.

It is estimated 11 that the total available horsepower on American farms as of January 1935, mechanical, wind, and animal, was about 72,763,000. The mechanical horsepower available was about 56 percent of the total, or 40,750,000 horsepower.11

The number of farm tractors in use has been reported by the United States Department of Agriculture to have increased from 80,100 in 1918 to 852,989 in 1929 and to 1,123,351 at the beginning of 1935.12

The power developed by all prime movers on American farms was estimated at 161⁄2 billion horsepowerhours during 1935 11 or the equivalent of about 11 billion kilowatt-hours. Mechanical power represented about 52 billion kilowatt-hours.

Isolated Nonindustrial Plants.-Under this classification are not included plants used in agriculture or in mines and quarries, but all other isolated plants such as are installed by the Government in public buildings, hotels, and for other stationary uses not included before. These are estimated to have a capacity of about 1,500,000 horsepower.

Motor Vehicles.-The motor vehicles of the United States have more available power than all other producers of power combined.

In 1935 there were in use in this country 22,589,660 automobiles, 3,511,061 trucks, 66,386 busses, and 95,633 motorcycles, a total of 26,262,740 motor vehicles.13 The entire world, outside of the United States of America, had in use in 1935 only 11,108,157 motor vehicles, which included 7,257,000 for all Europe, 1,926,231 for the Americas (except United States),

10 Data from census report of 1929 and from industrial report prepared by the national power survey.

11 Estimate by S. H. McCrory, Chief, Bureau of Agricultural Engineering, United States Department of Agriculture.

12 Aug. 1, 1935, issue of Farm Implement News.

13 Automotive Industries, statistical issue, Feb. 22, 1936.