Part 6

Footnote 13:

The unit of impact being that given by a body weighing one pound and moving one foot a second, the impact of such a body falling from a hight of 772 feet—the velocity acquired being 222¼ feet per second (=√(2sg))—would be 1 × (222¼)^2 = 49,408 units, the equivalent in impact of one heat-unit. A cannon-ball weighing 1000 lbs. and moving 1100 feet a second would have an impact of (1100)^2 × 1000 = 1,210,000,000 units. Dividing this by 49,408, the quotient is 24489 heat units, the equivalent of the impact. The specific heat of iron being ·1138, this amount of heat would raise the temperature of one pound of iron 215.191° F. (24,489 × ·1138) or of 1000 pounds of iron 215° F. 24489 pounds of water heated one degree, is equal to 136½ pounds, or 17 gallons U. S., heated 180 degrees; i.e., from 32° to 212° F.

Footnote 14:

Assuming the density of the earth to be 5·5, its weight would be 6,500,000,000,000,000,000,000 tons, and its impact—by the formula given above—would be 1,025,000,000,000,000,000,000,000,000,000 foot-tons. Making the same supposition as in the case of our cannon-ball, the final pressure would be that here stated.

Footnote 15:

TYNDALL, J., Heat considered as a mode of Motion; Am. ed., p. 57, New York, 1863.

Footnote 16:

RANKINE (The Steam-engine and other prime Movers, London, 1866,) gives the efficiency of Steam-engines as from 1-15th to 1-20th of the heat of the fuel.

ARMSTRONG, Sir WM., places this efficiency at 1-10th as the maximum. In practice, the average result is only 1-30th. Rep. Brit. Assoc., 1863, p. liv.

HELMHOLTZ, H. L. F., says: “The best expansive engines give back as mechanical work only eighteen per cent. of the heat generated by the fuel.” Interaction of Natural Forces, in Correlation and Conservation of Forces, p. 227.

Footnote 17:

THOMSEN, JULIUS, Poggendorff’s Annalen, cxxv, 348. Also in abstract in Am. J. Sci., II, xli, 396, May, 1866.

Footnote 18:

American Journal of Science, II, xli, 214, March, 1866.

Footnote 19:

In this calculation the annual evaporation from the ocean is assumed to be about 9 feet. (See Dr. BUIST, quoted in Maury’s Phys. Geography of the Sea, New York, 1861, p. 11.) Calling the water-area of our globe 150,000,000 square miles, the total evaporation in tons per minute, would be that here given. Inasmuch as 30,000 pounds raised one-foot high is a horse-power, the number of horse-powers necessary to raise this quantity of water 3½ miles in one minute is 2,757,000,000,000. This amount of energy is precisely that set free again when this water falls as rain.

Footnote 20:

Compare ODLING, WM., Lectures on Animal Chemistry, London, 1866. “In broad antagonism to the doctrines which only a few years back were regarded as indisputable, we now find that the chemist, like the plant, is capable of producing from carbonic acid and water a whole host of organic bodies, and we see no reason to question his ultimate ability to reproduce all animal and vegetable principles whatsoever.” (p. 52.)

“Already hundreds of organic principles have been built up from their constituent elements, and there is now no reason to doubt our capability of producing all organic principles whatsoever in a similar manner.” (p. 58.)

Dr. Odling is the successor of Faraday as Fullerian Professor of Chemistry in the Royal Institution of Great Britain.

Footnote 21:

MARSHALL, JOHN, Outlines of Physiology, American edition, 1868, p. 916.

Footnote 22:

FRANKLAND, EDWARD, On the Source of Muscular Power, Proc. Roy. Inst., June 8, 1866; Am. J. Sci., II, xlii, 393, Nov. 1866.

Footnote 23:

LIEBIG, JUSTUS VON, Die organische Chemie in ihrer Anwendung auf Physiologie und Pathologie, Braunschweig, 1842. Also in his Animal Chemistry, edition of 1852 (Am. ed., p. 26), where he says “Every motion increases the amount of organized tissue which undergoes metamorphosis.”

Footnote 24:

Compare DRAPER, JOHN WM. Human Physiology.