

.MINING SURVEYS 



HERE a mine is entered by a tunnel or where the 

 ore occurs in slopes not over about 60, the ordinary 

 transit with legible graduations and proper pro 

 tection against dust or moisture will answer every 

 purpose; but when the inclination of the sight cuts 

 through the horizontal plates, some provision must 

 be devised for auxiliary sighting in the observation 

 of both precipitous horizontal and heavy vertical 

 angles. 



I. If horizontal angles are to be read between points in 

 great declivity below the instrument or if alignments are to be pro- 

 longed in very steep inclined shafts, the auxiliary telescope, through 



Fig. gS No. 57 s-in. Tachymeter with Edge Graduated Vertical > 

 Kquippetl to Receive Auxiliary Telescope or Solar Attachment 

 Interchangeably on Same Swivel Mounting 



