566 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



154. Al Motanabi. The poems of AbuTaib, surnamed Al Motanabi. S. W. J. 



155. Dewan i Ali. The poems of Ali. S. W J. 



156. Dewan ul A'shak. A book of poems. S.W.J. 



157. Sharah i akayad i Mula Saduddin. A commentary on the Akayad, by Saduddin. S. W. J. 



158. Sharah ul Moalakat. A commentary on the Moalakat. I/. J. 



159. Sharah ul Mobarak. Another commentary on the Moalakat. I/. J. 



160. Kasayed sabah moalakah. The poems of Almutalammis. I/. J. 

 16*1. Kasayedul Musabba. Poems. I/. J. 



162. A'dabul Maluk. The manners of princes. L\ J. 



163. Behr ul Bask. I/. J. 



164. TaifulKhiyal. S.W.J. 



165. Moruj uz zeheb wa maaden ul Joher. An historical and geographical work, by Abul Hassan, 

 surnamed Masaudi. S. W. J. 



166. Hariri. The moral discourses of Hariri. S. W. J. 



167. An Arabic manuscript, traced on oiled paper. Probably that copy of the ancient Arabian poems, 

 called Hamasah, mentioned N° 1 53. I/. J. 



168. A new copy of a manuscript, in sheets. No name. L y . J. 



HINDOSTANI. 



169. Gulistan. Translated from the Persian. S. W. J. 



170. A commentary on the Grunt'ha, the religious institution of the Sic'hs, in the Nagari cha- 

 racter. 17. J. 



END OF THE EIGHTY-NINTH VOLUME OP THE ORIGINAL. 



I, The Croonian Lecture. On the Structure and Uses of the Membrana Tympani 

 of the Ear. By Everard Home, Esq. F. R. S. Anno 1800. Vol. XC. p. 1. 



The principal object of the present lecture is to communicate a discovery of the 

 structure of the membrana tympani ; which, in some respects, affords a new and 

 very curious instance of the application of muscular action, and may conduce to ac- 

 count for certain phenomena in the sense of hearing, in a more satisfactory manner 

 than has hitherto been proposed. The membrana tympani has always been con- 

 sidered as a common membrane, which, by means of muscles belonging to the 

 malleus being stretched or relaxed, became fitted, in its various degrees of tension, 

 to convey the vast variety of external sounds to the internal organ. Its shape, 

 situation, and office, have procured it the name of drum of the ear; and the muscles 

 of the malleus having been deemed sufficient for bracing and unbracing it, less at- 

 tention was bestowed on the structure of the membrane itself: to which may be 

 added, that in the human ear, and generally in the ear of quadrupeds, the mem- 

 brane is so extremely small and thin, and in its situation so peculiarly confined, as 

 not to be got at for inspection but with much difficulty. 



The case is different in the elephant, where this membrane is so very large, 

 that the parts of which it is composed are readily distinguished: they are even 

 conspicuous to the naked eye; and muscular fibres are seen passing along the 



