208 On the supposed Repulsion of Electricity. 



found in the shales both of the Newcastle coal-field, and in such 

 as do not lie very deep in the encrinal limestone formation gene- 

 lallv associated with the thickest seams of coal in that district. 

 The localities of these organic remains are tolerably numerous ; 

 but ironstone being an object of little consequence, notice has 

 seldom been taken of its beds or nodules, except when they have 

 been denominated whinstone girdles in the colliery sections. 

 Recurring to our numerous strata of shale, it is impossible to say 

 to which they do or do not belong. 



4 and .t. My reason for thinking that the red sand-stone of the 

 Tees is covered by the Whitby alum-rock, has been stated at 

 some length in my tract on the east part of Yorkshire ; but I have 

 jiot as vet been able to ascertain the fact. The paper in question 

 is by no means sufficiently perfect to meet the public eye; but 

 I flatter myself with the prospect of revisiting that part of the 

 kingdom during the course of the ensuing summer. 



May I nov/ hope that the gentleman who signs himself A Con- 

 stant Reader will inform me either by letter, or through -the me- 

 dium of your Magazine, 



1st, Whether he considers the Whitby alum shale, and the 

 clunch clay of Lincolnshire, the same stratum ; and if the coal- 

 field, covering the former, belongs to it, or is a distinct forma- 

 tion r 



2dly, What is the hard blue shell limestone quarried near 

 Therkleby, and how situated with res))cct to tiie oclite and coal 

 measures near it? also, what rocks are situated immediately above 

 and beiovv it ? 



An answer to these questions will greatly oblige, sir. 

 Your most obedient servant, 

 Newcastle-upon-Tyne, r^iarch 10, 1S17. N. J. \V. 



P. S. As a confirmation of Professor Buckland's position, that 

 the red sand-stone of the vale of Eden is not the old red sand- 

 stone, rocks of magnesian limestone' are associated with it at 

 Low House, between Armathwaite aud Corby. 



LIV. On the supposed Repidsion of Electricity. 



To Mr. Tilloch. 



Sir, — xxs the cause of the divergence of bodies equally elec- 

 trified does not appear to be generally understood, I have taken 

 the liberty of submitting the following observations, which, if 

 you think proper, you are at liberty to insert in your valuable 

 Magazine. 



1 am aware that Mr. Singer, in his excellent work on Elec- 

 tricity, 



