4 oo THE POPULAR SCIENCE MONTHLY. 



condensation, can hardly be sustained, and seems entirely overthrown 

 if we regard the single fact that, on the great equatorial belt the belt 

 of perennial precipitation no hurricane or typhoon has ever been 

 experienced by the mariner. It has long been, and is now, the 

 universally-accepted theory of meteorologists, that the reason no 

 cyclones have ever been known to occur on the equator is, that there 

 the earth's rotation exerts a deflecting influence on the winds, amount- 

 ing to zero, and hence the formation of a whirl is impossible. This 

 view is not satisfactory, because the nucleus of a depression once 

 formed on the equator, there would be intro-moving masses of air 

 proportioned in violence to the amount of the depression and the 

 steepness of the barometric gradient, down which they rush to reach 

 the point of lowest barometer. The true reason that no great cyclone 

 has ever been formed nearer the equator than the third parallels of 

 latitude appears to be, that the equatorial belt is a belt of calms. 



-- 



HEAT AND LIFE. 

 Bt fern and papillon. 



TRANSLATED FROM THE FRENCH BY A. R. MACDONOtTGH, ESQ. 



THE full solution of the question of heat and life could only be 

 reached by simultaneous concurrence of physics, chemistry, and 

 biology. Ancient physiology treated of animal heat empirically, but 

 was unable to explain its origin. That result required the discoveries 

 of Lavoisier and the more 'modern researches of thermo-chemistry. 

 After revealing the source of that heat, it was important to show how 

 it was disposed of; and this is taught us by thermo-dynamics. And, 

 in conclusion, only the most delicate physiological experiments could 

 settle the modifications that take place in living beings, when sub- 

 jected to the influence of a temperature either above or below that 

 they possess normally. Medicine and hygiene already benefit by the 

 indications yielded by pure science upon this subject. It is admitted 

 that the study of the variations of animal heat in diseases is of the 

 highest consequence for their comprehension, and that both diagnosis 

 and prognosis receive unexpected light from it. 



An inquiry into calorific phenomena, undertaken from various 

 separate and independent points of view, for the solution of questions 

 that seemed at first sight to have no mutual connection whatever, has 

 thus obtained a body of truths which enter into combination almost 

 of their own accord at the present time, and are found to contain 

 the secret of a great problem in natural philosophy. A minute and 



