A Defence of the nevo Theory of the Tides. 269 



sell of course is aware that the Newtonian philosophers account 

 for the ebbing of the tides by supposing that the moon, when 

 she is below the horizon, pulls the waters {obliquely) downwards 

 by the power of her attraction j and it must be very evident that 

 the nearer the moon comes to the earth the greater will be the 

 power of her attraction ; and also, as the direction or inclina- 

 tion of that power will be less oblique, the effect produced by 

 it will be so much the more. Now it is acknowledged by all 

 the astronomers, that the moon is nearer the earth on the full 

 and change days than when she is in her quarters ; and conse- 

 quently her power to press the waters downwards must be so 

 much the greater. Mr. Russell must also be aware, that at the 

 time of the spring tides the sun is always either in conjunction 

 or opposition with the moon ; but at the neap tides the power 

 of the sun's attraction is always opposed to that of the moon, 

 and is always pulling the waters upwards in those places where 

 the moon's attraction is pressing them down, that is, where it 

 is low water by the moon's tide ; so that the waters, at low wa- 

 ter, during the neap tides, must be so much higher than they 

 are at spring tides, as the sun's attraction has power to lift 

 them up. 



" The satisfaction " (says Mr. Russell) "which Mr. Forman 

 seems to derive from a handful of water is by no means enviable. 

 He speaks of the moon as if astronomers and philosophers 

 think its attractive power over substances on the face of the 

 earth equal to the attractive power of the earth itself: but I 

 believe there are very fev/ philosophers that are not satisfied of 

 the contrary. Surely he does not wish us to understand that 

 because the moon has no power to sustain a handful of water* 

 in the atmosphere, it has no power OTer it whatever. He may 

 as well attempt to teach us, that because a magnet has no power 

 to lift a scale beam, it has no power to disturb its equilibrium." 



If Mr. Russell had taken the pains to inform himself of the 

 cause of the equilibrium of a suspended weight (of iron) being 

 disturbetl by a magnet when the same magnet has not sufficient 

 power to lilt it u|i, he would never have ventured to make use 

 of it as an argument against my theory. If we suppose a body 

 to be suspended by a cortl, it is evident that the wJioie weight 

 of tliis body must be sustained by the cord ; but if this body 

 should be pushed away from the ))erpendiciihir by any jjcrson, 

 then tiie weiglit will be divided bulween this person and the 

 cord in proportion to tlie angle it makes with the perpendi- 

 cular. 'I'liiis llie touch of a child may be able to distmb the 

 equilibrium of a ton weiglit when it is suspended ; but it would 

 require a force that is able to lift five hundred weight to kee[) 

 ♦ And consequently lias no i)o\vcr to lift a Imndful oC water. 



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