on the. Motion of the Arm, 419 



cular and osseous systems in various animals, would form a 

 good foundation from whence, in future, to push forward such 

 inquiries; and, besides this remote and dubious utility, con- 

 tingent on the soundness of the foregoing speculation, such 

 researches would be of considerable immediate advantage to 

 science. They would give the geologist a new point of view 

 in which to examine fossil bones, and might enable him to 

 deduce, from the relative size, shape, and situation of the 

 marks indicating muscular insertion, new particulars concern- 

 ing the strength and speed of extinct creatures; they would 

 probably point out to the comparative anatomist analogies 

 and differences in the structure of animals, where none have 

 hitherto been suspected ; and above all, they would tend to 

 introduce into physiology an exactness and certainty which 

 the science has not yet attained. As a first step to such an 

 analysis, I intend shortly to attempt a set of experiments on 

 the contractility of the muscular fibre, by the several methods 

 that have just been described. Those who undertake such 

 researches should bear in mind that the friction of the tendons 

 is an important element of the calculation. Muscles which 

 are extended in a straight line between their attachments, and 

 undergo no friction but that of the investing cellular tissue 

 (as the gastrocnemius), have greatly the advantage of those 

 whose tendons play over trochlear surfaces (as the obturator 



or not, likely to suggest to its investigators some useful experiments, will 

 not be classed with the extravagant iatro-mathematical speculations which 

 retarded the progress of physiology in the seventeenth and beginning of the 

 eighteenth century. " Prudens quaestio dimidium scientiEe," says Lord 

 Bacon, a sentiment admirably elucidated by Herschel in the Preliminary 

 Discourse. " A well-imagined hypothesis," he says, " if it have been 

 suggested by a fair inductive consideration of general laws, can hardly fail 

 at least of enabling us to generalize a step further, and group together se- 

 veral such laws under a more universal expression, and we may thus be 



led to the trial of many curious experiments, and to the imagining ofmanv 

 useful and important contrivances which we should never otherwise have 

 thought of." To which may be added the following judicious remarks of 

 Mr. R. Young : " As in practice nothing is perfect, and few things wholly 

 without merit, so, in theories, perhaps, none are without error, nor any 

 devoid of truth. The difference between opinions seems to lie chiefly in 

 the different proportions of truth and error which they contain. If this 

 be true, every advance in principles is only substituting a less imperfect 

 theory for one more so, and the last ever leaves something for futurity 

 to correct." — (Essay on the Powers and Mechanism of Nature, p. ix.) 



[We may refer the reader, on the subject of numerical proportions in 

 animal organization, to our abstract of Dr. W. Adam's paper, " On the 

 Ostcological Symmetry of the Camel" in Phil. Mag. and Annals, vol. ix. 

 p. 364 : the paper itself will be found in the Transactions of the Linnaean 

 Society, vol. xvi. p. 525 et seq. See also Lond. and Edinb. Phil. Mag., vol. iii. 

 p. 457, vol. vi. p. 57, for notices of papers by Dr. Adam on the ostcological 

 symmetry of the human skeleton. — Edit.] 

 3 D 2 



