Beat 

 elpless 



SCIENTIFIC SIDE-LIGHTS 



300 



hothouses, altho there they must exchange 

 the perpetual equinox of their native re- 

 gions for days and nights which are alter- 

 nately protracted to nineteen hours and 

 shortened to five. How much farther to- 

 wards the pole they might continue to live, 

 provided a due quantity of heat and mois- 

 ture were supplied, has not yet been deter- 

 mined; but St. Petersburg is probably not 

 the utmost limit, and we should expect that 

 in lat. 65 at least, where they would never 

 remain twenty-four hours without enjoying 

 the sun's light, they might still exist. 

 LYELL Principles of Geology, bk. i, ch. 6, p. 

 89. (A., 1854.) 



1463. HEAT PRODUCING COLD Re- 

 frigeration Improves Food of Nations. 

 Since heat is transformable into motive 

 power, and motive power can force am- 

 monia to chill itself, a ton of coal, accord- 

 ing to quality, can make six to ten tons 

 of ice in competition with the frosts of win- 

 ter. Because their product is pure, re- 

 frigerating-machines are finding more and 

 more favor in cities once supplied exclu- 

 sively with ice from ponds and streams. 

 . . . Cold, so singular an issue of heat, 

 has high commercial value. Apples and 

 grapes harvested in September and October 

 are sent from the cold-storage warehouse 

 to the table in perfect order as late as May. 

 The fruit-grower and the dairyman have a 

 new opportunity to choose the time for 

 marketing their products. Refrigerator 

 steamships now carry Canadian butter and 

 New Zealand meat in vast quantities to the 

 markets of Great Britain. Within the 

 shorter distances traversed by the railroads 

 of the United States the strawberries of 

 Oregon find their way unbruised and fresh 

 to St. Paul and Chicago, while the kitchen- 

 gardeners of Florida and Louisiana look 

 for their customers in New England and 

 New York. There is more in all this 

 than the mere purveying of luxuries; there 

 is an increase of individual health and 

 strength when a national bill of fare is at 

 once diversified and made more wholesome. 

 Whereas heat in the hands of early man 

 served to multiply his foods by primitive 

 methods of roasting, of smoking, of pres- 

 ervation in grease as pemmican the later 

 applications of heat by the modern engineer 

 are of incomparable service in multiplying 

 the food-resources of the civilized world. 

 Cold storage and quick transportation sup- 

 plement in remarkable fashion every de- 

 vice that has sprung from the aboriginal 

 grill and kettle. ILES Flame, Electricity, 

 and the Camera, ch. 5, p. 66. (D. & McC., 

 1900.) 



1464. HEAT PROVED NOT A SUB- 

 STANCE Thermal Vibration Compared to 

 Sound of Bell. With regard to the illustra- 

 tion which compared heat to water con- 

 tained in a sponge, Rumford replied thus: 

 *' A sponge filled with water and hung by 

 a thread in the middle of a room filled with 

 dry air communicates its moisture to the 



air, it is true, but soon the water evaporates 

 and the sponge can no longer give out mois- 

 ture." The case, he contended, is not at 

 all similar to heat; for here, by renewed 

 mechanical action, we can cause the heat 

 to flow out at will. " A bell," he says, 

 " sounds without intermission when it is 

 struck, and gives out its sound as often 

 as we please, without any perceptible loss. 

 Moisture is a substance, sound is not." 

 Heat, he contended, was typified by the vi- 

 brating bell and not by the evaporating 

 sponge. TYNDALL Heat a Mode of Motion, 

 lect. 2, p. 46. (A., 1900.) 



1 465. HEAT, SUPPLY OF, WITHIN THE 

 EARTH Science May Yet Mine for Heat A 

 City Receives Hot Water from Underground. 

 So marked is this steady increase of tem- 

 perature as we go downwards, that it has 

 been seriously proposed to make very deep 

 borings in order to obtain supplies of warm 

 water for heating our towns. Arago and 

 Walferdin suggested this method for warm- 

 ing the Jardin des Plantes at Paris; and 

 now that such important improvements 

 have been devised in carrying borings to 

 enormous depths, the time may not be far 

 distant when we shall draw extensively 

 upon these supplies of subterranean heat. 

 At the present time the city of Budapest 

 is extensively supplied with hot water from 

 an underground source. Should our coal- 

 supply ever fail, it may be well to remember 

 that we have these inexhaustible supplies 

 of heat everywhere beneath our feet. JUDD 

 Volcanoes, ch. 12, p. 335. (A., 1899.) 



1466. HEAT SUPPOSED TO BE MAT- 

 TER Phlogiston Count Rumford' s Experi- 

 ment Heat Proved To Be Motion Errors 

 of Early Scientists. Down to the beginning 

 of this century heat was generally considered 

 to be a form of matter, termed caloric or 

 phlogiston. The presence of phlogiston was 

 supposed to -render substances combustible, 

 but when the chemical theory of combustion 

 was discovered by Lavoisier, phlogiston, as 

 the cause of combustion, disappeared, al- 

 tho caloric, as the material basis of heat, 

 still held its ground. Close to the end of 

 the last century Count Rumford showed 

 that in boring a brass cannon the heat de- 

 veloped in 2y 2 hours was sufficient to raise 

 26% Ibs. of water from the freezing- to the 

 boiling-point. But during the operation the 

 metal had lost no weight nor undergone any 

 other change; and as the production of heat 

 by this process appeared to be unlimited he 

 concluded that heat could not be matter, but 

 merely a kind of motion set up in the par- 

 ticles of matter by the force exerted. . . . 

 Such facts led to the conclusion that there 

 was a mechanical equivalent of heat that 

 is, that a certain amount of force exerted 

 or work done would produce a corresponding 

 amount of heat; and Joule was the first 

 to determine this accurately by a number 

 of ingenious experiments. The result was 

 found to be that a pound of water can be 

 raised 1 C. by an amount of work equal 



