136 



THE PROSPECTOR'S HANDBOOK. 



triangle, together with a Table of Sines (see Appendix), 

 may prove useful. 



Let x A B C bo a right-angled triangle. 



(i.) Perpendicular A B equals length A C multiplied by sin c. 

 Lase B c ,, AC sin a. 



Let A c represent two points on a hill-side, from which 

 respectively a shaft, A B, is to be sunk, and an adit, C B, 

 driven. Let B be the point where they may be supposed 

 to meet. Measure length A c, and suppose it to be 200 feet. 

 Measure either the vertical angle a (which is really 90-- 

 the clip of the hill-side) or else the angle c, which is the dip. 



Let a 50 30' ; and c = 39 30'. 



FIG. 65. 



Then by (i.) 



Perpendicular A B equals 200 feet x sin. 39 30'. 

 B c 200 X sin. 50 30'. 



Now by Table of Sines, sin. 39 30' is -6361, 

 and, sin. 50 30' is -7716. 



Therefore : perp. A B equals 200 feet x '6361. 

 base B c equals 200 feet x '7716. 



That is : perp. A B is 127-22 feet, 

 base B c is 154-32 feet. 



The length of the shaft is 127'22 feet, and that of the 

 adit 154-32 feet. 



