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CHAPTER II. 



THE FIGURE OF THE EABTH. 



1. Newton s calculation of the ellipticity of the earth its defects. 



2. An accurate investigation of the ellipticity on the supposition that the 



earth is homogeneous the form thus found proved to be stable. 

 Note IIL 



3. Newton s calculation of the law of variation of gravity. 



4. Newton s application of his theory to the planet Jupiter. 



5. The figure of the earth considered as heterogeneous, Clairaut and 



Laplace s results. Note IV. 



a. The form of the strata. 



/3. The law of variation of gravity. 



6. The law of density in the interior of the earth. Note IV. 



7. Whether the interior of the earth is solid or fluid. Note IV. 



8. Measures to determine by observation the ellipticity of the earth s 



surface. Note IV. 



a. Measurement of degrees, 



/3. Observations on the pendulum. 



7. Astronomical observations. 



1. IN the eighteenth proposition of the third book, New 

 ton considers why the earth and planets are protuberant at 

 their equator. He does not investigate the form of the earth, 

 but merely shows that if it had been originally fluid, the 

 matter, by its ascent towards the equator, would enlarge 

 the diameters there, and by its descent towards the poles 

 it will shorten the axis. And even if the earth had not 

 been originally fluid, yet if the earth were not higher at 

 the equator than at the poles, the seas would subside 

 about the poles, and rising towards the equator, would 

 lay all things there under water. 



Taking for granted that the true form of the earth is 



N 



