In projecting alignments in steep incline shafts the process of 

 this adjustment should be put into practice, so far as possible, on 

 every sight. If mine waters are acidic and corrode the axles, one 

 can never be certain that this important adjustment has not been 

 modified. The mechanical treatment of the bearing itself is a matter 

 of prime importance in the permanency of adjustment. 



(c) The easiest and most accurate method lor the standard 

 adjustment, and the one that provides the best control for triangu- 

 lation, or tunnel alignment, is unfortunately not much used because 

 of the exposed position of the Striding Level which is employed. 

 This method of adjustment is described on p. 131. 



Bausch & Lomb 4-inch Transit 



' 'Reconnaissance ' ' 



Specifications 

 Telescope Erecting, 8% in. extending to 9 in. long; aperture, 



l^g-in.; power, X18. Inverting, X16; transits at eye-end. 

 Telescope Bubble 3^ in. long, 2mm divisions, sensibility, 40". 

 Plate Bubbles \ l / z in. long, 2mm divisions, sensibility, 60". 

 Compass Needle I 1 /* in. long, tubular, sapphire mount, weight, 



0.47 grms. 



VerticalLimb 4-in. diam., minute graduations, adjustable vernier. 

 Horizontal Limb 2>-in. rad.;4&'-in. diam. outside graduations. 

 Standards Bronze, 4 Vie in- high, 2^-in. base. 

 Leveling Screws German silver, #$-in. head, dust caps. 

 Shifting Center ,^-in. range. 

 Height 9 in. with arc; 10 in. with circle. 

 Finish Gamboge yellow and Japanese black. 

 Weight b% Ibs.; in case with accessories, 1\J4 Ibs. 



Split leg tripod, 57-in. legs, 1^. Ibs. Ext. tripod, l]'i Ibs. 



Bausch & Lomb 5-inch Transit 



lt Surveyors" 



Specifications 

 Telescope Erecting, 10 in. extending to 11# in. long; aperture, 



1# in.; power, v- 20. Inverting, X20 or X28, transits at 



eye end only. 



Telescope Bubble 4V in. long, 2mm divisions, sensibility, 30". 

 Plate Bubbles 2 in. long, 2mm divisions, sensibility, 50 '. 

 Compass Needle 3J1j in. long, tubular, sapphire mount, weight, 



0.64 ; 



74 



