53if lioj/ctl Society. 



This paper contains the account of a great number of facts and 

 observations, collected from various sources, on the subject of the 

 relations subsisting between electricity, the proiluction of sound, the 

 crystallization of bodies, the transmission of heat, the emission of 

 light, and various atmosplieric changes ; from the consideration of 

 which the general conclusion is drawn that all these phsenomena are 

 perhaps the results of the undulations of some ponderable material. 



9. " Physiological Remarks on several Muscles of the Upper Ex- 

 tremity." By F. O.Ward, Esq., Medical Student at King's College, 

 London. Communicated by P. M. Roget, M.D., Sec. R.S.* 



There is a remarkable fold in the tendon of the pectoraiis major 

 musc!e, described by all anatomists, but the purpose of which has 

 never yet, as the author believes, been explained. The muscle itself 

 consists of two portions, one smaller and upper, arising from the cla- 

 vicle, and passing downwards and outwards to an insertion in the 

 humerus at a greater distance from the shoulder-joint than the place 

 where the tendon of the larger and lower portion of the muscle, which 

 arises from the sternum and ribs, and has a general direction upwards 

 and outwards, terminates. Thus the respective portions of tendon 

 belonging to the two divisions of the muscle are found to cross each 

 other ; the margin of that proceeding from the lower division passing 

 behind, and appearing above that which proceeds from the upper fibres 

 of the muscle. The forces exerted by each portion of the muscle 

 being thus applied to parts of the bone at different distances from the 

 fulcrum, act with different mechanical powers ; which the author finds 

 in every case to correspond exactly with the variations in (lie effects 

 required to be produced, under different circumstances, by these mus- 

 cular actions. Those muscular fibres, the tendon of which is inserted 

 nearest to tlie centre of motion, and which consequently act by a 

 shorter lever, are adapted to motions requiring a less force, but a 

 greater velocity : and such is ])recisely the mechanical condition of 

 the lower portion of the ])ectoralis major, which is employed more 

 especially in bringing down the arm, when previously raised, as in 

 striking with the hammer, pickaxe, &c., where velocity is chiefly re- 

 quired, the weight of the instrument held in the hand sufficiently sup- 

 plying the diminution of force. On the contrary, the lever by which 

 the upper portion of the same muscle is enabled to act being, from 

 the more distant insertion of its tendon, of greater length, is calcu- 

 lated to procure force at the expense of velocity, and is therefore pe- 

 culiarly fitted for the performance of those actions by which the arm 

 is elevated and weights raised ; these being precisely the actions in 

 which such muscles are employed. Adverting, also, to the respective 

 obliquities in the direction of their action, the author traces the same 

 express correspondence between the mechanism employed and the 

 purpose contemplated. He pursues the same line of argument and 

 obtains the same results in extending the inquiry to the structure and 

 uses of those muscles, such as the coraco-brachialis, and the anterior 

 fibres of the deltoid, which cooperate with the upper division of the 

 pectoraiis major ; and the teres major and latissiraus dorsi, which 



* Tills paper appears at length in our present number, p. 411. 



