20S On the Antilunar Tide. [Mahchj 



not fall freely to the sun, their respective gravities are not affected 

 by any tendency to separation. Holding it then proved, that the 

 eliptical figure of the moon's orbit is not produced by the endea- 

 vours of the sun, alternately to unite and divorce the naoon from 

 the earth ; and in like manner, that the antilunar tide is not pro- 

 duced by the endeavour of the sun to draw the bed of the ocean 

 away from the waters which repose on it, we shall proceed to the 

 exposition of that cause which it is apprehended does produce the 

 inferior or antilunar tide. 



Mr. M'Laurin lias somewhere considered the earth as composed 

 of concentric coats or layers. Let us adopt this idea. By the 

 moon's attraction, the particles of the hemisphere nearest to herj 

 are drawn y»OTO the centre, while the particles or layers of the in- 

 ferior hemisphere are drawn towards, or in the direction of, the 

 centre. If the superior hemisphere could yield to this force, and 

 fall towards the moon, the other no doubt would follow it. But, 

 as the case stands, as the superior hemisphere does not fall away, 

 the inferior hemisphere is resisted thereby, and the effects of the 

 moon's attraction is to draw the concentric coats or layers together* 

 Instead of separating them it unites them more closely. 



Attraction resisted is equivalent to pressure. The phenomenon 

 of water rising in a common pump, will afford a good illustration 

 of this important fact. The effect of working the piston is the 

 removal, from a portion of the surface of the water, of the superin- 

 cumbent weight, or pressure of the atmosphere. The waters in 

 the other parts, remaining subject to that pressure, and being pre- 

 vented by the resistance of the earth at the bottom from moving 

 in the direction of the attracting impulse, move towards that 

 quarter from which the pressure is removed. They continue to 

 accumulate on that spot till a column is formed which balances 

 the pressure of the atmosphere. They rise into the pump. But 

 the preisure of the atmosphere is nothing more than the attraction 

 or gravitation of the atmosphere towards tlie centre of the earth, 

 and the measure of the attraction is the measure of the pressure. 

 We thus find a general law governing a vast variety of the opera- 

 tions of nature. We find that as in the case of direct attraction^ 

 (that is where the movement of the attracted body towards the 

 body attracting is not resisted) the body most attracted leaves the 

 hody least attracted; so, tvhen attraction, or rather the motion of 

 the body attracted, is resisted, the reverse takes place; the body 

 least attracted leaved the body most attracted, but in an opposite 

 direction. Every ascent perpendicular from the centre ought, I 

 am persuaded, to be ascribed to the operation of this law. To it 

 appears to be owing the upright growth of vegetables, and to it I 

 would ascribe the swelling of the antilunar tide. 



The earth being supposed to have assumed that form which re- 

 sults from central attraction, and centrifugal force produced by 

 rotation, the moon's attraction may be considered, as Newton has 

 considered it, to be an additional force acting in parallel lines. 



