Aprils, 1895.] 



SCIENCE. 



371 



the day's work : which is equivalent to say- 

 ing tliat the ellieiency of this vital machine, 

 considered simply as prime mover, is 23i 

 per cent. If etticiencj- of conversion of 

 potential into dynamic energy of muscular 

 work, internal as well as external, is con- 

 sidered, it is very possible that this figure 

 may be doubled, and the efficiency to be 

 taken in comparison with that of heat- 

 engines may be somewhere between forty 

 and fifty per cent. If the internal work of 

 thought and of brain and nerve power is 

 considered useful work, and the total com- 

 pared with the energy supply, the efficiency 

 will be a still higher figure, perhaps fifty or 

 even sixty per cent.=^= 



But the highest total efficiency of the 

 best steam-engine yet constructed is but 

 about twenty per cent., with its thermody- 

 namic range of about 200° F. (111° C.) 

 degrees, Fahr., and that of the best gas-en- 

 gine is but about the same, with a range 

 of ten times that extent. If the vital ma- 

 chine be a thermodynamic engine, there- 

 fore, it.s known efficiency, with no recog- 

 nized temperature, range of heat ' letdown,' 

 is not less than twenty-five per cent, higher 

 than, and may be twice as high as, the best 

 heat-engines constructed by man. Tliis is 

 recognized by engineer and thermodyna- 

 mist alike, as a reductio ad absnrdum, and the 

 vital engine is certainly not a heat-engine. 



The facts regarding the distribution of 

 potential energy to the various organs of 

 the body; the dovelojiment by each organ 

 of its special form of product in new compo- 

 sitions or in a special energy ; the localiza- 

 tion of energy-transfoi'mations in the cells 

 of the muscle, or other energy-producer; 

 the accompahj'ing liberation of carbon- 

 dioxide from consumption of glycosic ma- 

 terial ; the utilization of a telegi-aphic, or 

 rather a semaphoric, system communication 



*Weisbach'sMechanic«of Engineering ; Kankine's 

 Prime Movei-8 ; Tliurston's Animal as a Trinie Motor ; 

 Keynolds' Memoir of ,7oule. 



between the mind or the interior automaton 

 of the spine and cerebellum and the point 

 of useful application of energy all : these 

 are fiiuiiliar to all ithysiologists.* Beyond 

 these known phenomena lie the mysteries 

 which the engineers, if possible more than 

 the physiologists themselves, most desire 

 to see completely solved. When thej' are 

 thoroughly investigated and the oi)erations 

 of the vital machine become fully known, 

 in all their details of energy-transformation, 

 it may be possible to secure new prime 

 movers of similarly high efficiency and thus 

 to double the life of the I'ace by prolonging 

 the period marking the endurance of our 

 supplies of potential energj' in the coal- 

 fields of the world. Should it prove that 

 only by preliminary manufacture of fuel, 

 in the form of sugars, can this result be 

 attained, it may seem unlikely that, even 

 when these operations are no longer mj-s- 

 teries, commercial applications of nature's 

 methods can be expected to prove success- 

 ful; yet when it is considered that the 

 sugars are simply carbon and water, it will 

 not be denied bj^ either engineer, chemist 

 or physiologist that a possibility still re- 

 mains of effecting so enormously important 

 an advance in the prime motors. If, further, 

 nature's economies in light-production can 

 be paralleled, the engineer may ultimately 

 furnish heat, light and power, the three 

 gi-eat products of his special labors of most 

 value to the race, with insignificant wastes 

 and approximately perfect efficiencj' and 

 maximum cheapness. Given perfect eflS- 

 ciency of power-production and the main 

 problem is solved. R. H. Thurston. 



Cornell University. 



IIARSHBERGER ON THE OIIIGIX OF OUR 



VERNAL FLORA. 

 By way of a review of a paper bj' Mr. 

 Henry L. Clarke, in the American Natural- 



* Foster's Physiology; Encyclopsedia Britanniav. 

 Art. Physiology; Chauveau's Le Travail Musculairc. 



