Earth as deducedfrom Experiments witkthe Pendulum. M£ 



larity has hitherto been experienced beyond the tropics; and 

 even between the tropics there are only a few stations at 

 which so great an excess of gravity has been observed as ex- 

 cludes them from belonging to the same surface as the other 

 experiments. I apprehend it cannot be said at present that 

 the great anomalies alluded to, are so well ascertained as to 

 render any further inquiry unnecessary in regard to their ex- 

 act quantity, or to the causes which produce them : and the 

 determination of these points in preference to any other, seems 

 to claim the attention of the experimenter ; because it must 

 fix in a great degree the complexion of the whole theory. 

 Can we hope to determine an elliptical surface that will re- 

 present ail the experiments within the limits of the probable 

 errors of observation ? Or, must we be content with a mean 

 elliptical figure liable to great discrepancies ? These seem at 

 present to be the most interesting questions in this research. 

 The least attention to the position of the anomalous stations 

 on the surface of the globe, will prove how fruitless it would 

 be, to suppose that the experiments can be better represented 

 by a figure different from the elliptical spheroid. Far less can 

 we expect, in the present state of our knowledge, to attain any 

 useful purpose by pushing the theoretical solution of the figure 

 of the earth to quantities of the second order ; because the 

 corrections thus introduced must be ultimately determined by 

 the experiments themselves, the uncertainties of which greatly 

 surpass the quantities to be found. 



I remain, Gentlemen, 



Your obedient servant, 

 March 12, 1828. J. Ivory. 



XL. Remarks on the Geology of the North Side of the Vale 

 of Pickering. By John Phillips, F.G.S., Keeper of the 

 Museum of the Yorkshire Philosophical Society* 



[With an Engraving.] 

 HPHE principal object of this communication is to explain 

 • some of the peculiar appearances which are exhibited 

 along the southern edge of the oolitic hills which margin the 

 Vale of Pickering from Seamer to Helmsley. 



My attention was first drawn to a part of this country by a 

 visit to Kirkdale Cave, in company with Mr. Salmond and 

 Mr. Smith, in March 1824. In August of the same year I had 

 further opportunity of examining with the aid of a barometer, 

 the whole line during my walk from York to Scarborough. 



* Read to the Yorkshire Philosophical Society, Jan. 1, 1828; and com- 

 municated by the Author. 



2 I 2 In 



