Proceedings of the British Association. 123 



they may pass from the middle to the division into thirds, or from a 

 point placed on a line dividing the external form into three equal parts, 

 and then approaching the middle, so as to form, with the fellow, two 

 parts of a triangle. He illustrated this rule by applying it to the entire 

 course of the artery of the upper extremity, and its principal divisions, 

 from the subclavian to the palmar arches, and from the course of the 

 occipital arteries. He remarked, that the common mode of dissecting 

 arteries and dried preparations was calculated to lead into serious 

 errors, in consequence of which he had been in the habit of teaching re- 

 lative anatomy, by successive removal of the layers placed above them, 

 so as not to disturb their lateral connexions. The position of the three 

 facial nerves, where they emerge from their foramina, illustrate the same 

 rules, being placed on vertical lines, dividing a well-formed face into 

 three equal parts. Prof. Macartney laid down exact rules for finding 

 the exact points of their emergence. He was not aware that any at- 

 tempts to lay down proportional measurements had been made in Eng- 

 land as a guide in operations, though a few rules have been laid down 

 on this subject by Lesfranc and Manec, in France. After forty-one 

 years' experience of those rules, he could relate numerous cases of their 

 great value in operations, and of the unfortunate results of ignorance of 

 such guides, in cases where operations were performed. In conclusion, 

 he showed that the same primary relations of two and three regulate 

 the progressive movements of animals provided with extremities, and 

 determine also their powers of perception and comparison; and that 

 they constitute the foundation of the rhythm of music and of language. 

 These positions he illustrated by reference to the perceptive powers of 

 man as exercised by the different senses, particularly those of sight and 

 hearing. 



' On the Cause of the Increase of Small-pox, and of the Origin of 

 Variola-vaccinia,' by Dr. Inglis. — Dr. Inglis stated, that variola was 

 every year upon the increase, the cause of which was, not that vaccina- 

 tion was inefficient, or that the virus had degenerated, but that, from a 

 long immunity from small-pox, the public had ceased to think vaccina- 

 tion necessary ; and he suggested that government should be petitioned 

 by the Medical Section of the British Association to enforce (as is done 

 aboard), not only the vaccination of every child born in the kingdom, 

 but the re-vaccination of every man in the British Service. He next ad- 

 duced proofs from the cow-pox Institution of Dublin, from foreign re- 

 ports, and from the innumerable cases of successful re-vaccination, that 

 the vaccine virus had not degenerated, but that the human system did 

 undergo a change during some unknown number of years. In Ripon, 

 during the year 1837, variola prevailed extensively as an epidemic, and 

 Dr. Inglis observed at that time innumerable cases of varicella ; those 

 affected with chicken-pox, were principally children upon whom vacci- 

 nation had not recently been performed, and those who had chicken-pox, 

 without vaccination, seldom contracted small-pox. The two diseases 



