of Metalliferous Veins by Cross-veins. 181 



per cent. 



Of the lodes yielding both tin and copper ores . . . 37*2 



... copper lodes 17*7 



Of all the lodes the proportion heaved towards the right- 



hand is 51»1 



Of the tin lodes . . . . » 56'0 



... lodes yielding both tin and copper ores . . . 44'0 



... copper lodes 52*4 



Of all the lodes the proportion heaved towards the left- 

 hand is 26*2 



Of the tin lodes . 26'0 



... lodes yielding both tin and copper ores . . . 18'6 



... copper lodes 29*8 



Of all the lodes the proportion heaved towards the greater 



angle is 63*5 



Of the tin lodes 52'0 



... lodes yielding both tin and copper ores . . . 56*0 



... copper lodes 74*2 



Of all the lodes the proportion heaved towards the 



smaller angle is . 12*9 



Of the tin lodes 30*0 



... lodes yielding both tin and copper ores . . . 6*8 



copper lodes 8'8 



The mean distance of the heaves feet. 



Of all the lodes is 16*4 



tin lodes 15*4 



lodes yielding both tin and copper ores . . 14*6 



copper lodes 17'5 



Towards the right-hand 18*7 



left-hand 12*0 



greater angle 16*3 



smaller angle 17*1 



Gongo Soco Gold Mines, Brazil, W. J. HENWOOD. 



October 5, 1843. 



XXX. On the Determination of the Distance of a given point 

 on the Earth's Surface at, or very near, the level of the sea, 

 by observations on its depression from a known height above 

 it. By William Galbraith, Esq., F.R.A.S. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



SHOULD the inclosed short paper meet with your appro- 

 bation, you will oblige me by giving it a place in your 

 Journal. It is intended as an improved solution of that pro- 

 blem in Horsburgh's edition of Mackenzie's Treatise on Marine 



