188 



posited ; the greatest quantity of iron being collected together at 

 that part. 



2ndly, That this point is endued with the same kind of attraction 

 as the pole of the hemisphere where the ship is : consequently, in 

 New Holland, the south end of the needle would be attracted by it, 

 and the north end repelled. 



3rdly, That the attractive power of this point, in a ship of war, is 

 sufficiently strong to interfere with the action of the magnetic poles, 

 upon a compass placed upon or in the binacle. 



The above suppositions, Capt. Flinders thinks, will account for all 

 the observed differences : and, admitting this opinion to be well 

 founded, it ought, he says, to follow, that when the ship is on the 

 north side of the magnetic equator, the differences in the variation 

 of the magnetic needle, arising from a change in the ship's head, 

 must be directly contrary to those above described. A few observa- 

 tions are given, which tend to confirm this opinion, and which also 

 seem to show that the variation is more westerly when taken upon 

 the binacle of a ship whose head is westward in north latitude, than 

 when observed in the centre of the ship. 



Capt. Cook having observed a considerable variation in the com- 

 pass while taking some observations upon Pier Head, on the coast of 

 New Holland, Capt. Flinders thought it right to make some fresh 

 observations at that place. He found, as Capt. Cook had done, that 

 the stones which lay on the surface of the ground did not produce 

 any sensible effect upon the needle, but that a considerable variation 

 took place, by a change of situation of a few yards only, at the top 

 of the hill. Whether this arises from a particular magnetic substance 

 lodged in the heart of the hill, or from the attractive powers of all 

 the substances of which Pier Head is composed being centered in a 

 point, similar to what Capt. Flinders has supposed to happen in a 

 ship, is, he says, a question he shall not attempt to decide. 



The Physiology of the Stapes, one of the Bones of the Organ of Hear- 

 ing ; deduced from a comparative View of its Structure and Uses 

 in different Animals. By Anthony Carlisle, Esq. F.R.S. Read 

 April 4, 1805. {Phil. Trans. 1805,;?. 198.] 



The bones of the organ of hearing, or ossicula auditus, in man and 

 in the mammalia, form, Mr. Carlisle says, a series of conductors, whose 

 office seems limited to the conveyance of sounds received through the 

 medium of air ; no parts corresponding to such bones being found in 

 fishes. In two of the classes of animals, however, namely, birds, and 

 the amphibia of Linnaeus, there is only one ossicle of the tympanum, 

 which is in the situation of the stapes. 



Mr. Carlisle then proceeds to give a minute description of the 

 human ossicula auditus, especially of the stapes. This description 

 we shall pass over, that we may be the more particular in our account 

 of the varieties observed in the last-mentioned bone in other animals. 



The configuration of the stapes, or indeed of the other ossicles, is 



