1814] On the AntUiniar Tide. 209 



Suppose farther, that the earth were a liollow globe, * liaving a 

 sliallow coverini:; of water on tlie interior and concave surface, as 

 well as on the exterior and convex surface ; and that the attractions 

 on the interior and exterior waters on each side were equal. Then, 

 as to the hemisphere nearest the moon, the waters on the interior 

 and exterior sides, being affected by equal forces, would exhibit 

 opfjosife effects. The exterior water being more attracted at the 

 equator than at the quadratures, and being allowed to fail towards 

 the attracting body, would be most drawn from the surface, and 

 would raise a tide at the equator, while the interior waters, being 

 7no>t af traded at the equator, but being resisted by the bed of earth 

 on whicli they rested, would be regulated by the laws of pressure, 

 and would flow towards the quadratures, where the attraction or 

 the pressure would be least. In like manner, as to the inferior or 

 ant'dunar hemisphere, the quadratures l^eing nearer the moon than 

 the equator, and the water on the interior side being most attracted 

 at the quadratures, and allowed to fall towards the moon, would in 

 that place be most drawn from the surface, and rise into polar tides : 

 whereas, the waters on the exterior surface, being resisted by tliat 

 surface, would f\ow from the quadratures, where the pressure would 

 be greatest, and accumulate at the equator, where the pressure 

 would be least. The two exterior tides would rise near the equa- 

 tor, and the two interior tides would rise near the poles. Abstract 

 now, the supposed circumstance of a hollow globe, and contem- 

 plate the earth as it is, a solid spheroid : — the same laws and the 

 same phenomena remain. The lunar tide rises because it is more 

 drawn from the earth at the equator tJaan at the quadratures ; and 

 the antilunar tide rises, because it is less drawn towards the earth 

 at the equator than at the quadratures. In the one case it is direct 

 attraction, or attraction unresisted : in the other it is attraction re- 

 sisted, or pressure. This theory may be further illustrated by the 

 common example drawn from the principles of equilibrium. Sup- 

 pose two columns of water, one at the equator, and the other at 

 the quadrature, but connected so as the water might flow from the 

 one to the other, they would, if equally attracted, stand at equal 

 heights. If a weight be applied to the column of water at the 

 quadrature, and not to that at the equator ; or if the pressure of the 

 atmosphere be withdrawn from the column at the equator, and not 

 withdiawn at the quadrature, it is evident from these principles 

 already noticed, which govern the rise of water in the common 

 pump, that the water would accumulate in the column exposed to 

 the least jjressure, till the accunnilated water in the one column 

 balanced the water and additional weight, or pressure, in the other. 



• Sec plali" XVI, fipure 16, .it p.nge 48, where A rp|)rcs(»nts ttip supposed shell 

 •r cruit »{ llic emth; U, the inieiiur surfare of the intciior waters at iiiialV-cted 

 U> any atlractiuo ; C, thcjnterior -urfacc of the exterior w ater in the !<ame state ; 

 L», the iiiirrior surface of Ihe interior »v;iter» as allerU'd .y atlr.iclion ; C, the 

 exterior 4urra( e of the citerior watursas affected by attraction j 1', F, F, parallel 

 \\nr% of aitrartiui). 



Vol. Hi. N°IiI. O 



