The Variation in Attraction Due to the Attracting Bodies. 241 



The increase in the density of liquids ciused by pressure, as shown by 

 Oe- sted's apparatus and other experiments, varies as the pressure, meas- 

 ured under the condition of constant temperature. Gasses f illow the same 

 law. Eesshanel says, " The true compiessihility of wa'er, according to re- 

 cent experiments conducted under the direction of M. Jamin, by Messrs. 

 Amaury and Descamps, is at the temperature of 15" Centigrade .0000427 

 per atmosphere." In tliese experiments the compressibility of glass was 

 taken to be 0000029 per atmosphere. The fact thdt solids can hi com- 

 pressed shows that solids pussess the fluid property essential to compressi- 

 bility. The fact that rocks are found beat which once were straight, also 

 that a pane of glass or a slab of marble can be bent by a certain continued 

 pressure demonstrates that the particles of solids can move on each other. 

 The movements of Si Jid ice in glaciers is proof in tlie same direction. The 

 effect of pressure above and belo>v the columns left for suppor s in deep 

 mines gives like testimony. The deep canyons of Colorado permit the 

 water to cut so deep and no deeper, because below a certain depth the solid 

 rock bottom like putty, rises from weights of high banks. 



It is the theory of the geologist that the earth, below a thin solid crust, 

 begins to become plastic, and at certain small depth becomes so p'astic 

 that the temperature thence to the cent r can only slightly increase, owing 

 to the law of convection of heat If the theory of the geologist be true, 

 then the increase in the density of the interior of the earth caused by 

 pressure varies as outride pressure. It is only in the c ise the theo y is not 

 true that we need ti'ouble ourselves ahout the shadow of a doubt that re- 

 mains in reference to the law of cjmpressibility of fiu:ds applying to sol- 

 ids. 



If computations made by formulas already developed, modified by the 

 condition of the theory of the geologist, builds up the earth fi-om center 

 to surface in layers, giving the diflference of gravity of corresponding 

 layer points in polar and equatori^il radius in harmony from center to sur- 

 face an I exactly meets the observed diflference of gravity at the surface, 

 likewise for ellipticity of layers so as to meet t e observed ellipticity at 

 surface, also giving a computed direction for gravity at the surface at any 

 latitude exactly in agreement with thf^ observed direction, then it seems to 

 me it must be accepfce I that the theory of the geologist is truth, and that 

 the t*^ eory of the astronomer, based on computations made from uncertain 

 data is a fallacy. 



16 



