415 



correctness of whose views is established by so many important dis- 

 coveries. 



On the Attractions of an extensive Class of Spheroids. By James 

 Ivory, A.M. Communicated by Henry Brougham, Esq. F.R.S. 

 Head November 14, 1811. [Phil. Trans. 1812, p. 46.] 



In his second paper, Mr. Ivory investigates the attractions of that 

 particular class of spheroids mentioned in the former ; for though it 

 is to these that the theorems of Laplace may strictly be applied, it is 

 liable to the important objection, that the terms of his series near 

 the beginning cannot be found without previously computing all the 

 rest. The analysis of Mr. Ivory, on the contrary, is direct ; and every 

 term of his series is deduced directly from the radius of the spheroid. 



In an appendix to these papers, Mr. Ivory adds some remarks upon 

 a memoir of Lagrange, upon the same subject, published at Paris in 

 December 1809, but which had not till lately been received in this 

 country. 



An Account of some Peculiarities in the Structure of the Organ of 

 Hearing in the Balcena Mysticetus of Linnaeus. By Everard Home, 

 Esq. F.R.S. Read December 12, 1811. [Phil. Trans. 1812, p. 83.] 



From the time that Mr. Home discovered the muscular structure 

 of the membrana tympani in the elephant, he has been seeking an 

 opportunity of prosecuting the same inquiry on a similar scale, by 

 examining the ear of a whale, and has at length succeeded in pro- 

 curing the head of a young whale preserved in brine. As the skin 

 had been taken off, a portion of the meatus externus had been re- 

 moved along with it ; but it did not appear that much was lost, as 

 the outward extremity partook of the dark colour of the outer skin 

 of the head. This passage was 65 inches in length, and only one 

 fourth of an inch in diameter ; but near the tympanum it widened to 

 about Ijf inch, and this is the breadth of the membrana tympani 

 itself. 



This membrane, instead of being concave externally as usual, is 

 convex, so as to project nearly an inch into the meatus externus. The 

 membrane consists of four parts : first, a cuticular covering, next a 

 strong membrane, then a layer of muscular fibres ; and lastly, an- 

 other membranous lining towards the tympanum. It is remarkable 

 that this membrane has no connexion whatever with the handle of 

 the malleus, as in other animals. 



The cavity of the tympanum is of an oval shape, capable of con- 

 taining a pint of fluid, surrounded by the concave surface of a large 

 bone peculiar to the whale, detached from the skull, and having only 

 a loose connexion with the petrose portion of the temporal bone. 

 This cavity terminates, as usual, in the eustachian tube, which is 

 2^ inches long, terminating by a small aperture, having a valvular 

 structure, and opening into the canal leading to the blow-hole. 



