0« a New Theory of the Tides. 89 



To t1i£ Members of the Astronomical Society. 



Gentlemen, — As yon have thought it necessary, in a paper 

 addressed to the pubHc, to call the attention of astronomers to 

 that branch of astronomy which is connected with the rising 

 of the tides, it is evident, that in your opinion the old h}-po- 

 thesis is not quite satisfactory ; or at least that you wish to be 

 fiirnished, by those who have had the opportunities of wit- 

 nessing their phaenomena in different parts of the world, with 

 such additional facts and documents as may either fully establish 

 the old theor}', or lead to the discovery of a better. 



In obedience then to this call, I beg leave to submit to your 

 judgement a Treatise on the Tides, which I have just written, 

 and which, by taking in the compressibility of water as a co- 

 operating principle, will account for several very important 

 phaenomena that cannot be explained in any other way. Thus, 

 for instance, if the compressibility of water be admitted in a 

 stifficieiit degree^ as the moon's attraction (being in opposition 

 to the earth's) must take off a portion of the gravity of every 

 particle of water, these particles must necessarily expand in 

 proportion to the weight that is taken off them ; and, as the 

 sum of the expansion of a great many particles must be a great 

 deal more than the sum of the expansion of a few, we shall 

 have a considerable rising in the deep parts of the ocean, with- 

 out any sensible alteration in lakes and shallow water. Thus, 

 then, if we admit the compressibility of water in a sufficient 

 degree, we shall have a principle that will satisfactorily explain 

 why the flood tide, in all places, always comes from the ocean; 

 why there are no tides in lakes and some inland seas ; why 

 the tides do not rise to the same height in all places where tlie 

 moon is equally vertical ; and lastly, why other loose substances 

 are not raised by the power of the moon's attraction as well as 

 water. But how can we account for all this, if we den}- the 

 compressibility, and consequently the expansion, of water ? 



If the moon's attraction, co-operating with the centrifugal 

 force of bodies, is capable of raising the tides in the ocean, 

 why does it not also raise the waters in lakes and ponds ? and 

 why are not all other loose substances affected in the same 

 man)ier ? If the earth, as was supposed by Newton, is con- 

 stantly drawn towards the moon by the power of her attrac- 

 tion, and the waters on the same side, l)y being so juuch nearer 

 than the central parts of the eartli, are made to move so much 

 faster, and thus are raised above their ordinary level, why are 

 not all (jther loose substances, that are equally near, raised in 

 the same manner? There is only one answer cay be given to 

 these questions. None of th<jse substances are elastic; but 



Vol. 60. No. 292. Aug. 1 822. M water 



