Mr. Kingston on the Iron Mine at Hay tor, Devon. 359 



fortresses, before breaches, and to defend bridges and passes, 

 wherever an enemy is likely to attempt a surprise. They 

 might also be placed around field works likely to be at- 

 tempted by assault. They would require to be sunk a little 

 in the ground, so that the splinters of one might not derange 

 those near to it, and covered lightly over to protect them from 

 wet, and also to conceal their position from an enemy. 



This principle might also be applied to the firing of artil- 

 lery by percussion ; more particularly at sea, where the roll of 

 the vessel presents so great an obstacle to accuracy of fire. In 

 that case, the vent of the gun would require to be placed a 

 little on one side, to be clear of the line of sight, and a hole 

 drilled through the spring opposite the vent, to allow the flash 

 from it to escape. The support of the spring would, of course, 

 be pulled away by a string, so that the man who laid the gun 

 might also fire it. 



LVIL Account of 'the Iron Mine at Hay tor, in Devonshire. By 

 J. T. Kingston, Esq. 



To the Editors of the Philosophical Magazine and Annals. 



Gentlemen, 



A MINERAL production discovered at the Haytor Iron 

 ■**■ Mine having formed the subject of two or three papers 

 in your valuable Journal *, you may perhaps consider a de- 

 scription of the mine itself not unworthy of occupying a page 

 or two of your next Number ; especially as it is, at least to 

 the best of my knowledge, the only one of the kind hitherto 

 discovered in this island, and as such, of some importance in 

 a geological as well as in an ceconomical point of view f. 



The lode, to the depth at present explored, is a very regu- 

 larly stratified one, of oxidulated iron ore and argillaceous 

 schist, in alternate beds ; and is situated on the edge of the 

 granite district, near the base of the Haytor rocks. The hill, 

 on the brow of which, near the centre, it crops out, is imme- 

 diately incumbent on the granite ; its principal slope is gra- 

 dual and towards the East, the sides having a more precipi- 

 tous descent to the North and South. It consists chiefly of 

 micaceous passing into clay schist, and of trapf (provincially 



* See Phil. Mag. and Annals, N.S. vol. i. p. 38, 40, 43. 



\ Some particulars of the vein of ore worked in this mine, will be found 

 in Mr. W. Phillips's paper on Haytorite, which is the first of the communi- 

 cations just referred-to. — Edit. 



\ Mr.W- Phillips, we observe, has stated that this substance appears to 

 be siliceous schist. — Edit. 



termed 



