122 Proceedings of the British Association. 



one parts of oxygen, and seventy-nine of carbonic acid, and death follow- 

 ed instantly from immersion in it ; and the same result followed when 

 the proportion were reversed, although a taper burned brilliantly in the 

 latter combination ; showing, that the burning of a light in any suspect- 

 ed situation is not always a safe test of the absence of danger. The se- 

 cond opinion is, that this gas, when respired, exerts a specific poisonous 

 action on the nervous system. This latter, Dr. Bird adopts, from various 

 considerations drawn from his direct experiments, and from the symp- 

 toms observed in numerous cases. These are principally those denomi- 

 nated cerebral, such as head-ache, vertigo, suffused eyes, mental horror 

 to an intense degree. Even with these symptoms, respiration may go 

 on freely. Death is frequently preceded by vomiting, which is a marked 

 symptom of cerebral disease. In cases where recovery has taken place, 

 the sequelae are decidedly of nervous character : they have been, partial 

 paralysis, dumbness, and idiotcy ; and this poisonous effect he thought 

 took place independently of absorption, from its immediate effects on 

 the nervous system, to which it was applied. Death has also been in- 

 duced by its external application to the body, without its being, at the 

 same time, respired. Dr. Bird related some experiments of Dr. A. T. 

 Thomson, in which the pain of inflamed surfaces was instantly removed 

 on their being plunged into carbonic acid. He dwelt on the pathologi- 

 cal effects of the gas as exhibited after death, and concluded by pressing 

 the importance of minute post mortem examinations in every case of 

 death from this cause coming under the notice of medical men. 



A member stated from his own experience, that in the burning of 

 charcoal a quantity of carbonic oxide is generated in many instances, 

 and this must be taken into account in any accurate examinations of the 

 question. — Prof. Macartney observed, that when the egg which has been 

 for some time in process of incubation is placed in carbonic acid, and the 

 temperature preserved, the developement of the chick ceases ; and this 

 he deemed a strong proof of the action of the gas being on the nervous 

 system, as in this case there is no respiration, and the process supple- 

 mentary to it is not at all interfered with. 



Prof. Macartney then read a paper ' On the Rules for finding with 

 exactness the Position of the principal Arteries and Nerves, from their 

 relations to the external forms of the body.' — He first alluded to the fact 

 demonstrated by painters and sculptors, that the proportions which 

 belong to the external figure of the human body are, in general, regulated 

 by the primary relations of duplicates and thirds, and their multiples ; 

 and that he had discovered that a similar law of proportion prevailed 

 with respect to the internal parts of the body — more particularly with 

 regard to the trunks of the arteries and nerves, in relation to the limits 

 of external form. They sometimes take a middle line along the limb, as 

 may be observed in the sciatic nerve, but more frequently they occupy 

 lines dividing the external form into thirds, or proceed from the median 

 line of the side of an extremity to the middle of the opposite side ; or 



