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400 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, amounting 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.



HE 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 subjected 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 