Had sider, for example, the enormous expansion of automotive transportation. gasoline not been available, we should have provided not millions of automobiles and thousands of miles of highway, but light railroads and electric traction lines instead. The electric vehicle, whose growth has been arrested by cheap gasoline, would have met a large part of the present requirement for automotive transportation, and its batteries would have been charged with coal-produced energy. New water-power developments reduce by just so much the potential demand for coal power. This invisible competition between the several sources of power is fully as significant as the visible substitution of fuel oil in a plant originally built to burn coal. The question is really, "Is the country's aggregate demand for power and heat-or 'energy,' to use a single word-falling or rising? How much of that aggregate demand is being met by means of coal? How much by means of fuel oil, gasoline, kerosene, and natural gas? How much by means of falling water?" The problem is largely one of measuring the relative rates of growth of these sources of energy. Table 7 shows the total supply of energy available in the United States excluding the small amounts furnished by firewood and work animals. To combine water power, oil, and coal it is necessary to have a common denominator. For this purpose the heating value in British thermal units of the fuels will suffice, and in the table the total production of each fuel has been converted into trillions of British thermal units. The figures for oil and gas were courteously furnished by G. B. Richardson, of the Geological Survey. Water power is represented in the table by the British thermal units of fuel which it would have been necessary to burn in order to give the same amount of power. Natural gas, in the early years before the accurate record begins, is represented by the estimated quantity of coal displaced by gas. The table goes back to 1819, to the very beginning of coal mining, in order to show the trend. Up to 1913 every tenth year is shown. Beginning with 1918 the record for each year is given. TABLE 7.—Annual supply of energy from mineral fuels and water power, 1819-1923 [Figures represent trillions of British thermal units, and because of rounding do not always add across exactly. Water power is represented by British thermal unit of coal necessary to produce the same amount of power. Figures represent production, and those for oil imports take no account of changes of stocks] No figures for water power are available prior to 1889. The fuel equivalent for water power is calculated from the reported horsepower of installed water wheels, assuming a capacity factor of 20 per cent for manufactures and mines and of 40 per cent for public utilities, and assuming that the theoretical thermal equiva lent of 1 horsepower-hour (2,547 British thermal units) is 7 per cent of the British thermal units that would have been consumed in generating 1 horsepower-hour from fuels in practice. For 1919 to 1923, however, actual reports of the horsepower-hours produced by water in electric utility plants have been used. Less than 0.5. • No data. Based on the amount of coal displaced by gas as estimated by the gas companies at the time. •Were allowance made for additions to stocks of coal and oil in 1923, the energy for that year would appear less. The unit heat values employed in this calculation are as follows: Anthracite, 13,600 British thermal units per pound; bituminous coal (with due allowance for lignite), 13,100 British thermal units per pound; oil, 6,000,000 British thermal units per barrel; and natural gas, 1,075 British thermal units per cubic foot. Figures showing trillions of British thermal units are not intelligible to anyone, even to fuel chemists, but their meaning becomes clear in Table 8, which shows the relative rates of growth. If the supply of any one of the competing sources of power in 1918 is expressed by the number 100, then the supply in any other year can be easily expressed as an index number or percentage of the base year, and in this way the rates of growth of the several competitors can be quickly compared. TABLE 8.-Relative rates of growth of coal, oil, and water power, 1819-1923 [The figures for the year 1918 are represented by the number 100, and the figures for all other years are expressed as a percentage of the 1918 rate] It would be misleading to contrast years like 1919, 1921, or 1922, which were marked by strikes or general business depression, with the prosperous year 1918. Instead let us take 1923, when general business was booming and the coal market was stimulated by the demand for extra tonnage to build up the depleted stocks. In comparison with 1918, the output of anthracite in 1923 had fallen 6 points and is represented by the number 94; the output of bituminous coal had fallen 3 points and is represented by 97. Contrast this with the change in oil and gas. Production of domestic oil had more than doubled, rising to the index number 205. Natural gas shows a large increase. Imported oil, which has now become a large factor in the energy supply of the country, rose to three times the 1918 rate in 1922, and even in 1923 stood at index number 218. Thus, while the total supply of coal had declined in importance, the total supply of oil and gas had greatly increased. Adding together all the oil and all the gas, their sum in 1923 was 91 per cent above that in 1918. Even water power has shown a material increase. There is no complete information as to the number of horsepower-hours produced from water, but the best estimates available indicate that they rose from 1918 to 1923 by 30 or 35 per cent. Now by combining all the sources of power into one index number, we can tell whether the country's total demand for power has been declining. If the total heat units contributed in 1918 by coal, oil, gas, and water power put together are represented by the number 100, then the heat units contributed in 1923 by all these sources are represented by the number 112. In other words, the total energy consumption of the country instead of falling off in 1923 showed an increase of 12 points over even 1918. As shown by the slope of the curve for total energy in Figure 33, the trend of growth from 1918 to 1923 is a not unnatural prolongation of that before 1918. Remembering that this index represents energy units produced, without regard to the fact that utilization in the meantime has become more efficient, it appears that the country's appetite for power and heat has continued to increase at a rate very close to normal, An increasing rate of total energy consumption coupled with a decreasing rate of coal production shows very clearly that some other source of energy has been displacing coal. What that other source is will be clearer from Figure 34, which shows the percentage of the total energy supply from mineral fuels that was contributed by each source in the years under consideration. Thus far we have been speaking of rates of growth without regard to the size of each item. A great increase in a small item may mean little. We have been accustomed to think of oil and gas as a small item in comparison with coal. FIGURE 33.-Relative rates of growth of bituminous coal, oil and gas, water power, and total energy, 18791923. In recent years oil and gas and water power have enjoyed a rapid rise at the expense of coal. The total energy has not kept up entirely with the trend of earlier years, owing, perhaps, to the greater effi ciency in the use of fuel, but the figures are not far from what may be regarded as normal. Coal, however, has taken a downward trend. The diagram makes no allowance for changes in stocks of the fuels during the year; were such allowance made, the figures for 1923 would be smaller This opinion was perhaps justified in pre-war years, when oil and gas furnished but 10 or 12 per cent of the total energy supply, but it will have to be scrapped now that in 1923 oil and gas had so far increased as to contribute 26 per cent of the total energy from mineral fuels (Table 9). In 1918 oil and gas contributed but 15 per cent of the total energy from fuels. To put it another way: In 1918 the heating value of coal was to the heating value of all oil and gas nearly as 6 is to 1; in 1923 the ratio was as 3 is to 1. Water power, though it has increased since the war faster than item in comparison with fuel. Its contribution to the energy country is only 4 or 6 per cent as great as that supplied by fuels. petitor of coal therefore is not water power but oil, 9786°-26-34 coal, is a small supply of the The real com FIGURE 34.-Percentage of total heat value furnished by each mineral fuel, 1819-1924 TABLE 9.-Percentage of total heating value contributed by the several mineral fuels, 1819-1923 • No figures for water power prior to 1889 are available. Hence to make the figures comparable, the data for water power thereafter are expressed as percentage of the fuel total but are not included in the base on which the percentage is computed. Less than 0.1 per cent. • Figures from 1869 to 1899 based on estimated quantity of coal displaced, COAL METHOD OF COLLECTING THE STATISTICS VOLUNTARY COOPERATION The principal statistics for each State during the last three years are given in Table 2 (pp. 501-503). These statistics are obtained from the producers' written reports, most of them signed by officers of the companies that furnish the figures. The reports are collected by correspondence, which is supplemented by visits of field agents if correspondence has failed. The Geological Survey has no power to subpoena records or to compel the filing of reports or to punish producers for rendering false reports. Under this system accurate results can be obtained only by the generous cooperation of the producers in furnishing returns voluntarily. The operators generally make cordial responses to the Survey's questionnaires, with which they have become familiar through more than 40 years of contact and cooperation, so that a very large percentage of the returns are obtained by mail, leaving relatively few to be obtained by personal visits. Accurate statistics might not be obtained under a system of voluntary reporting if information was requested which the persons addressed were reluctant to furnish or concerning which they had a motive to misrepresent the facts. No questions of this character are asked by the Survey on its annual report forms, except possibly the questions concerning the value of the product and the occurrence of strikes. In 1923, as in 1922 and 1920, a number of operators declined to state the value of the coal they sold. The number and the importance of these failures to make returns and the method used by the Survey in estimating the values not reported are explained on page 617. The possible errors in the returns dealing with strikes are discussed in Mineral Resources, 1922, Part II, pages 512-518. The other questions asked by the Geological Survey in its annual schedule deal with the physical operation of the mines. The operators The can obtain no advantage by concealing or misstating these facts, for the facts could be definitely ascertained from other sources. operators' returns may be checked against the records of the departments of mines in States that commonly publish them and against the records of coal shipped by the railroads, which must agree in the aggregate with the reports made by the operators of coal tendered for shipment. These checks are sufficient to warrant public confidence in the substantial accuracy of the returns, subject to the limitations stated in presenting this report. Whether the voluntary system of reporting may be safely used as to inquiries concerning costs, prices, profits, and other financial matters is a different question. Geological Survey has found it difficult, for example, to reconcile the statements of car supply voluntarily furnished by the railroads with the statements of time shut down for lack of cars voluntarily furnished by the mines, and it is aware that the current reports on time worked and lost by the mines published in its weekly coal statement contain very serious errors. The |