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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



length and with great fertility of illustration. It 

 is shown, for instance, in the case of the galvanic 

 battery, that the amount of heat developed by 

 the slow consumption of a certain weight of zinc 

 is approximately identical with what would be 

 produced by its rapid combustion in oxygen; 

 and that whether this energy be applied to the 

 heating of an outer wire, or to effecting chemical 

 changes, as in the decomposition of water, or to 

 the production of mechanical work, the result, 

 or (H-{-W), is always a constant quantity. Wher- 

 ever work is done, it has to be paid for. " No 

 engine, however subtly devised, can evade this 

 law of equivalence, or perform on its own ac- 

 count the smallest modicum of work." 



The learned writer than proceeds to inquire 

 if the animal body is to be classed among machines. 

 In ascending a mountain, lifting a weight, or 

 throwing a stone, we are conscious of exerting 

 force ; and every such exertion is proved to be 

 attended by a perfectly definite consumption of 

 fuel (say carbon) in the muscles, which performs 

 just as much work as its combustion out of the 

 body would effect. The identity of this mode of 

 action with that of a steam-engine or a galvanic 

 battery is then sought to be proved, on the 

 ground that here also (H-j-W) is a constant 

 quantity. As this is the very core of the argu- 

 ment, and that to which I propose to apply the 

 testing question, "Is it true ? " I will not run any 

 risk of misrepresenting it by any attempt at con- 

 densation, but will give it in extenso, in the very 

 words of the author : 



" Let us look to tlie antecedents of this force. 

 "We derive the muscle and fat of our bodies from 

 what we eat. Animal heat you know to be due to 

 the slow combustion of this fuel. My arm is now 

 inactive, and the ordinary slow combustion of my 

 blood and tissue is going on. For every grain of 

 fuel thus burned a perfectly definite amount of heat 

 has been produced. I now contract my biceps 

 muscle without causing it to perform external 

 work. The combustion is quickened and the heat 

 is increased, this additional heat being liberated 

 in the muscle itself. I lay hold of a fifty-six pound 

 weight, and by the contraction of my biceps lift it 

 through the vertical space of a foot. The blood 

 and tissues consumed during this contraction have 

 not developed in the muscle their due amount of 

 heat. A quantity of heat is at this moment miss- 

 ing in my muscle which would raise the tempera- 

 ture of an ounce of water somewhat more than 1° 

 Fahr. I liberate the weight; it falls to the earth, 

 and by its collision generates the precise amount 

 of heat missing in the muscle. My muscular heat 

 is thus transferred from its local hearth to external 

 space. The fuel is consumed in my body, but the 



heat of combustion is produced outside my body. 

 The case is substantially the same as that of the 

 voltaic batteiy when it performs external work or 

 produces external heat. All this points to the 

 conclusion that the force we employ in muscular 

 exertion is the force of burning fuel and not of 

 creative will. In the light of these facts the body 

 is seen to be as incapable of generating energy 

 without expenditure as the solids and liquids of 

 the voltaic battery. The body, in other words, 

 falls into the category of machines. We can do 

 with the body all that we have already done with 

 the battery — heat platinum wires, decompose water, 

 magnetize iron, and deflect a megnetic needle. The 

 combustion of muscle may be made to produce all 

 these effects, as the combustion of zinc may be 

 caused to produce them. By turning the handle 

 of a magneto-electric machine, a coil of wire may 

 be caused to rotate between the poles of a magnet. 

 As long as the two ends of the coil are uncon- 

 nected we have simply to overcome the ordinary 

 inertia and friction of the machine in turning the 

 handle. But the moment the two ends of the coil 

 are united by a thin platinum wire a sudden addi- - 

 tion of labor is thrown upon the turning arm. 

 When the necessary labor is expended, its equiv- 

 alent immediately appears. The platinum wire 

 glows. You can readily maintain it at a white 

 heat or even fuse it. This is a very remarkable 

 result. From the muscles of the arm, with a tem- 

 perature of 100°, we extract the temperature of 

 molten platinum, which is many thousand degrees. 

 The miracle here is the reverse of that of the burn- 

 ing bush mentioned in Genesis. There the bush 

 burned but was not consumed, here the blood is 

 consumed but does not burn. The similarity of 

 the action with that of the voltaic battery when it 

 heats an external wire is too obvious to need point- 

 ing out. When the machine is used to decompose 

 water, the heat of the muscle, like that of the bat- 

 tery, is consumed in molecular work, being fully 

 restored when the gases recombine. As before, also, 

 the transmuted heat of the muscles may be bottled 

 up, carried to the polar regions, and there restored 

 to its pristine form. The matter of the human 

 body is the same as that of the world around us, 

 and here we find the forces of the human body 

 identical with those of inorganic Nature." » 



When in a certain kind of evening entertain- 

 ment we have our watch taken from our pocket, 

 beaten to atoms in a mortar, fired from a pistol, 

 and otherwise maltreated, we know that it will in 

 some way or other be restored to us, sound and 

 perfect as before, perhaps from the middle of a 

 yesterday's loaf, perhaps cut from the centre of a 

 fruit grown to maturity on the table before our 

 eyes. All this, however, is the very A B C of 

 conjuring, compared with this effort of modern 



1 Times report, October 2. 1877. 



