SCIESCE AXD MAX. 



101 



thernic-pile itself is always from bismuth to an- 

 timony, across the heated junction — a direction 

 in which it cannot possibly establish itself with- 

 out consuming the heat imparted to the junction. 

 This heat is the nutriment of the current. Thus 

 the heat generated by the thermo-current in a 

 distant wire is simply that originally imparted to 

 the pile, which has been first transmuted into 

 electricity, and then retransmuted into its first 

 form at a distance from its origin. As water in 

 a state of vapor passes from a boiler to a distant 

 condenser, and there assumes its primitive form 

 without gain or loss, so the heat communicated 

 to the thermo-pile distills into the subtiler elec- 

 tric current, which is, as it were, recondensed into 

 heat in the distant platinum wire. 



In my youth I thought an electro-magnetic 

 engine which was shown to me a veritable per- 

 petual motion — a machine, that is to say, which 

 performed work without the expenditure of 

 power. Let us consider the action of such a 

 machine. Suppose it to be employed to pump 

 water from a lower to a higher level. On ex- 

 amining the battery which works the engine we 

 find that the zinc consumed does not yield its 

 full amount of heat. The quantity of heat thus 

 missing within is the exact thermal equivalent 

 of the mechanical work performed without. Let 

 the water fall again to a lower level, it is warmed 

 by the fall. Add the heat thus produced to 

 that generated by the friction, mechanical and 

 magnetical, of the engine, we thus obtain the 

 precise amount of heat missing in the battery. 

 All the effects obtained from the machine are 

 thus strictly paid for; this "payment for re- 

 sults " being, I would repeat, the inexorable meth- 

 od of Nature. 



No engine, however subtly devised, can evade 

 this law of equivalence, or perform on its own ac- 

 count the smallest modicum of work. The ma- 

 chine distributes, but it cannot create. Is the ani- 

 mal body, then, to be classed among machines ? 

 When I lift a weight, or throw a stone, or climb a 

 mountain, or wrestle with my comrade, am I not 

 conscious of actually creating and expending 

 force? Let us look to the 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 bsen pro- 

 duced. I now contract my biceps muscle with- 

 out causing it to perform external work. The 



combustion is quickened and the heat is increased, 

 this additional lieat 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 tis- 

 sue consumed during this contraction have not 

 developed in the muscle their due amount of heat. 

 A quantity of heat is at this moment missing in 

 my muscle which would raise the temperature of 

 an ounce of water somewhat more than one degree 

 Fahrenheit. 1 liberate the weight, it falls to the 

 earth, and by its collision generates the precise 

 amount of heat missing in the muscle. My mus- 

 cular 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 battery when it per- 

 forms external work or produces external heat. 

 All this points to the conclusion that the force we 

 employ in muscular exertion is the force of burn- 

 ing 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 magnetic needle. The combustion of 

 muscle may be made to produce all these effects, 

 as the combustion of zinc may be caused to pro- 

 duce 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 unconnected 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 addition 

 of labor is thrown upon the turning arm. When 

 the necessary labor is expended, its equivalent 

 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 temperature 

 of 100°, we extract the temperature of molten 

 platinum, which is many thousand degrees. The 

 miracle here is the reverse of that of the burning 

 bush mentioned in Exodus. There the bush 

 burned but was not consumed : here the body 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 



