1 74 Archdeacon Pratt on the Level of the Sea during 



ern hemisphere 



= 0*6 sin2<£ - g, and acts towards the north pole. 

 a 



Hence 



0*6 sin 2cj)-g = horizontal attraction of northern 



meniscus towards north pole 



- (0-1446 sin + 0-0958 sin 20 + 00244 sin 30) -#. 



Also 0=18O°-0. Hence 



Horizontal Attraction of northern meniscus towards the north pole 



= (0-1446 sin <j> + 0-5042 sin 2</> + 0-0244 sin 30) -g. 



3. Having thus obtained the force of attraction, I will find 

 its effect on the level of the ocean on which the ice-sheet floats, 

 wherever the ocean is not itself frozen. I may observe also that 

 it is not necessary to suppose that the meniscus is altogether one 

 unbroken solid mass. There may have been here and there 

 comparatively small pools or lakes or canals of unfrozen water, 

 in which the water would be lifted up by the attraction of the pre- 

 ponderating mass of solid attracting matter, and when so lifted 

 up, nearly at any rate to the proper level, would itself attract 

 nearly as much as the ice which would have taken its place had 

 the whole been frozen. 



If U is a force acting horizontally on the ocean at a point of 

 which the distance measured along LPs line of action is u, then 

 the rise of the ocean owing to this force 



= - I Vdu, between the proper limits*. 



For U put the expression above deduced; also du——d.a§. 

 Then, integrating from the equator, where = 90°, 



Rise of the Level of the Ocean 



= |0'1446 cos </> + 0'2521 (cos 20 + 1) + 0O081 cos Scf>\ h miles. 



4. I will apply this to two latitudes, viz. 45° and 60°, or 

 = 45° and = 30°. These give as the rise 0*3486^ and 

 0*5033 h miles, if h is expressed in miles, and the attracting 

 matter be rock ; or 0*1162^ and 0'1678A feet, if h be expressed 

 in feet, and ice be the attracting matter. 



Mr. Croll takes h to be 7000 feet. This gives the rise of 

 the ocean in latitudes 45° and 60° to be 813 and 1175 feet. 



5. These heights of the ocean above its present level may have 



* See 'Figure of the Earth,' 3rd. edit. p. 156. 



