Page:Proceedings of the Royal Society of London Vol 1.djvu/208

Rh 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. Flinrlers 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 bones of the organ of hearing, or ossicula auditﬁs, in man and in the mammalia, form, Mr. Carlisle says, a series of conductors, whose ofﬁce seems limited to the conveyance of sounds receiifed 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 auditﬁs, 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