COO ntAQMKNTS OF SCIKNCK 



looked, lie makes ready room in his recognition or his 

 reverence. But no retrospect of scientific literature has as 

 yet brought to light a claim which can sensibly affect the 

 positions accorded to two great Path-newer s, as the 

 Germans call them, whose names in relation to this subject 

 are linked in indissoluble association. These names are 

 Julius Robert Mayer and James Prescott Joule. 



In his essay on " Circles" Mr. Emerson, if I remember 

 rightly, pictured intellectual progress as rhythmic. At a 

 given moment knowledge is surrounded by a barrier which 

 marks its limit. It gradually gathers clearness and 

 strength until by and by some thinker of exceptional power 

 bursts the barrier and wins a wider circle, within which 

 thought once more entrenches itself. But the internal 

 force again accumulates, the new barrier is in its turn 

 broken, and the mind finds itself surrounded by a still 

 wider horizon. Thus, according to Emerson, knowledge 

 spreads by intermittent victories instead of progressing at 

 a uniform rate. 



When Dr. Joule first proved that a weight of one pound, 

 falling through a height of seven hundred and seventy-two 

 feet, generated an amount of heat competent to warm a 

 pound of water one degree Fahrenheit, and that in lifting 

 the weight so much heat exactly disappeared, he broke an 

 Emersonian " circle," releasing by the act an amount of 

 scientific energy which rapidly overran a vast domain, and 

 embodied itself in the great doctrine known as the " Con- 

 servation of Energy." This doctrine recognizes in the 

 material universe a constant sum of power made up of 

 items among which the most Protean fluctuations are 

 incessantly going on. It is as if the body of Nature were 

 alive, the thrill and interchange of its energies resembling 

 those of an organism. The parts of the "stupendous 

 whole" shift and change, augment and diminish, appear and 

 disappear, while the total of which they are the parts 

 remains quantitatively immutable. Immutable, because 

 when change occurs it is always polar plus accompanies 

 minus, gain accompanies loss, no item varying in the 

 slightest degree without an absolutely equal change of 

 some other item in the opposite direction. 



The sun warms the tropical ocean, converting a portion 

 of its liquid into vapor, which rises in the air and is 

 rt'coudensed on mountain heights, returning in rivers to 



