838 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



and the eyes of the two then meet. It is an interesting confirmation of the 

 principles here advocated, that when binocular vision cannot be obtained by 

 directing the true axes of the eyes towards the object, as happens when an 

 opaque spot exists upon the centre of the cornea, or an artificial pupil has 

 been formed at the margin of the iris, there is an automatic tendency to the 

 neutralization of the mischief, by such an action of the muscles as shall turn 

 the virtual axis of the affected eye (that is, the axis in which the rays most 

 directly enter the globe) towards the object, thus producing Strabismus, but 

 not Double Vision. 



3. Energy and Rapidity of Muscular Contraction. 



687. The energy of Muscular contraction is of course to be most remark- 

 ably observed, in those instances in which the continual exercise of particular 

 parts has occasioned an increased determination of blood towards them, and 

 in consequence a permanent increase of their bulk ( 334, m). This has 

 been the case, for example, with persons who have gained their livelihood by 

 exhibiting feats of strength. Much will, of course, depend on the mechan- 

 ically advantageous application of muscular power; and in this manner 

 effects may be produced, even by persons of ordinary strength, which would 

 not have been thought credible. In lifting a heavy weight in each hand, 

 for example, a person who keeps his back perfectly rigid, so as to throw the 

 pressure vertically upon the pelvis, and only uses the powerful extensors of 

 the thigh and calf, by straightening the knees (previously somewhat flexed), 

 and bringing the leg to a right angle with the foot, will have a great advan- 

 tage over one who uses his lumbar muscles for the purpose. A still greater 

 advantage will be gained by throwing the weight more directly upon the 

 loins, by means of a sort of girdle, shaped so as to rest upon the top of the 

 sacrum and the ridges of the ilia ; and by pressing with the hand upon a 

 frame so arranged as to bring the muscles of the arms to the assistance of 

 those of the legs : in this manner, a single Man of ordinary strength may 

 raise a weight of 2000 Ibs. ; whilst few who are unaccustomed to such exer- 

 tions, can lift more than 300 Ibs. in the ordinary mode. A man of great 

 natural strength, however, has been known to lift 800 Ibs. with his hands ; 

 and the same individual performed several other curious feats of strength, 

 which seem deserving of being here noticed. "1. By the strength of his 

 fingers, he rolled up a very large and strong pewter dish. 2. He broke several 

 short and strong pieces of tobacco-pipe with the force of his middle-finger, 

 having laid them on the first and third finger. 3. Having thrust in under 

 his garter the bowl of a strong tobacco-pipe, his legs being bent, he broke it 

 to pieces by the tendons of his hams, without altering the bending of the 

 knee. 4. He broke such another bowl between his first and second fingers, 

 by pressing them together sideways. 5. He lifted a table six feet long, which 

 had half a hundred-weight hanging at the end of it, with his teeth, and held 

 it in that position for a considerable time. It is true, the feet of the table 

 rested against his knees ; but as the length of the table was much greater 

 than its height, that performance required a great strength to be exerted by 

 the muscles of his loins, neck, and jaws. 0. He took an iron kitchen poker, 

 about a yard long, and three inches in circumference, and holding it in his 

 right hand, he struck it on his bare left arm between the elbow and the wrist, 

 till he bent the poker nearly to a right angle. 7. He took such another 

 poker, and, holding the ends of it in his hands, and the middle of it against 

 the back of his neck, he brought both ends of it together before him ; and, 

 what was yet more difficult, he pulled it straight again." Haller mentions 



1 Desaguliers's Philosophy, vol. ii. 



