NATURAL PHILOSOPHY. 135 



When a ray of light falls upon- a daguerreotype plate, forming part of a 

 galvanic circuit, which includes a galvanometer and Breguet's metallic ther- 

 mometer, there is instantaneously and simultaneously produced chemical 

 affinity on the surface of the plate, an electric current in the galvanometer, 

 an elevation of temperature in the thermometer, motion in the two needles 

 of the galvanometer and thermometer, etc. As a concrete and striking 

 example of homogenesis, we may instance what we will term the human 

 machine, that masterpiece of creative power. It is sustained solely, first by 

 alimentary provision, composed of carbon, hydrogen, nitrogen, and assimi- 

 lative mineral principles, then by atmospheric air introduced by respiration. 

 The vital phenomenon, par excellence, is the combustion of carbon and 

 hydrogen by the oxygen of the atmosphere a combustion which, it ap- 

 pears to us, is summed up in a first disengagement, in a first motion, in a 

 first circulation. Now, observe to what this first motion gives birth: a very 

 intense heat, which maintains our whole body, even in winter, at a temper- 

 ature of ninety-eight degrees Fahrenheit; an electric or nervous current, of 

 which M. Helmholtz has established the existence and measured the velocity; 

 the circulation of the blood in the entire system of arteries and veins; a 

 mechanical force sufficient to transport the entire body which, upon an 

 average, weighs 100 pounds, with a velocity of several yards per second; 

 the muscular force exercised by the various organs, which make of an active 

 man one of the strongest animals in creation; chemical affinity, under a 

 thousand different forms, with the very complex series of combinations and 

 decompositions, assimilations and secretions, etc. : evidently, this is not only 

 the correlation of physical forces, it is also their homogenesis, their mutual 

 transformation, their identity in cause and also in nature, etc. 



NEW COSMICAL FORCE. 



Jacobi, of St. Petersburg, well known to the scientific world for his fine 

 researches on light and magnetism, has recently thrown out some remark- 

 able ideas on the necessity of introducing into calculations of the planetary 

 system a new force, besides gravitation, namely, induction. The numerous 

 practical applications of the remarkable force, electro-magnetism, he says, 

 have rather pushed out of sight the vast importance of the discovery in a 

 purely scientific point of view, and observes that he has no scruple in 

 placing it by the side of gravitation as a force in celestial mechanics Here 

 are a few of the most intelligible links in his chain of reasoning: All bodies 

 are magnetic to a greater or less degree; the earth is a vast magnet, and it 

 is doubtless the same with other planets and their satellites, and even with 

 the sun himself. Now it is a general law, and also a fact proved by every- 

 day experience, that when two bodies, both permeated by magnetic currents, 

 approach or recede from each other, their approach or their recession gene- 

 rates contrary currents of induction. And it is these currents of induction, 

 with their consecutive and perturbative attractions or repulsions, that he 

 proposes to introduce into the explanation of the phenomena of celestial 

 mechanics. 



INFLUENCE OF LIGHT IN GRAVITATION. 



The following is an abstract of an essay on the above subject, by Dr. Wm. 

 S. Green, of Muscogee County, Georgia : 

 1. It is argued that gravitation is an action of contiguous atoms of matter, 



