E.. Frankland on the Source of Muscular Power. 393 
tint, possess a close general accordance with those of « Orionis, 
8 Pegasi, and the absorption spectrum of the remarkable object 
described in this paper. The purely speculative idea presents 
itself from these observations, that hydrogen probably plays an 
important part in the differences of physical constitution which 
apparently separate the stars into groups, and possibly also in 
the changes by which these differences may be brought about.* 
Art. LIII.—On the Source of Muscular Power; by EDWARD 
FRANKLAND, Ph.D., F.R.S." 
Wuart is the source of muscular power? Twenty years ago, 
if this question had been asked, there were se few philosophers 
who would have hesitated to reply, “The source of muscular 
return such a reply. We at Sie ow that an animal, however 
high its organization may be, can no more generate an amount 
of force capable of ries A a re vof sand, than a stone can 
' fall upwards or a locomotive drive a train ‘without fuel. _ 
that such an animal can do is to liberate that store of force 
potential energy, which is locked up in its food. It is the = sd 
weal change which food suffers in the body of an animal that lib- 
erates the previously pent-up forces of that food, which now 
make their appearance in the form of actwal energy—as heat and 
mechanical motion. 
— food, and food — comes the mailer of which the 
mal body is built up; and from food alone come all the dif- 
este: kinds of physical force whisk an animal is capable of man- 
ifestin 
The” two chief forms of force thus manifested are ~~ and 
Muscular motion or mechanical work, and these have been almost 
universally ‘steed to two distinct sources—the heat to the ‘oxy 
* Mr. Rapesdelt Cah re ee poh g Be oe, of ee: 
May o GM. T, ==3'6 or 3°7 magnitude. 
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* From the Proce. Roy. Inst. of Great Britain, June . oe 
