"Of course, in all these cases, the max! mum error has been under 

 consideration. The average error in computations would be much 

 less, although for strict consistency of results the maximum error is 

 the controlling factor. 



"These curves should be useful to the surveyor or engineer in 

 enabling him to decide quickly and accurately the limiting size of 

 angles if he desires consistently accurate results, and whether or not 

 more refined instruments or methods of measuring angles will be 

 necessary under any given conditions. Other uses of the curves 

 will be evident in any connection where computed results depend 

 on measured angles." 



The Interchangeable Auxiliary Telescope 



Fifc. 105 No. 457 4^-inch Theodolite with Kdfire Graduated Vrr 

 Circle Showing Kkctric Hand Magnifier, also Interchange- 

 able Auxiliary Telescope Applied to Side of 

 Instrument. 



The interchangeability of the auxiliary telescope has great!) 

 improved and facilitated mine <uu \r\ s by puulucing a single positive 

 result from a double negative condition. With the ordinary fixed 

 top or side telescope, great ini; . II been justly attached to 



parallelism of collateral sighting: but in the case of the interchange- 

 able auxiliary, if the adjustment for alignment is maintained for all 



