- When the auxiliary is applied to the top of the instrument, 

 it is securely mounted on the same "solar table" with swivel adapter 

 as supplied for the Solar Attachment. This mechanical principle is 

 nearly if not quite unique andobviates the necessity of fixinga vertical 

 pillar to the top of the main telescope. In this position, horizontal 

 angles may be observed without correction if the vertical wires are 

 ranged into the same alignment. The adjustment for parallelism 

 is not necessary, but if the operator prefers to secure this relationship 

 he may follow the directions under the head of Adjustments. The 

 least accessible station may be sighted with the auxiliary, and the 

 other with the main telescope. The eyepiece prism may be used 

 interchangeably when the circumstances require it. The collima- 

 tion being correct in both telescopes for all distances, the auxiliary 

 may be mounted with its eyepiece towards the main objective, but 

 must be adjusted in alignment against some previously established 

 test line, which limits this practice to rare occasions. 



Fig. 106 shows the individual axis of revolution with which 

 our auxiliary telescopes are equipped. The little clamp-and-tangent 

 is used to range the auxiliary into alignment with the main telescope. 

 The illustration shows the auxiliary turned off to one side as in 

 slope-stake work, which indicates the possibility also of setting the 

 auxiliary at exactly 90, or at any desired angle with the main tele- 

 scope for city surveys or any such work where fixed deflections can 

 be established while the main telescope is horizontal. 



The scheme is also recommended for tracing concealed outcrops 

 on hillsides, if the auxiliary can be set to the dip and strike of the 

 vein at any exposed portion. 



Slope Stake Setting 



In setting slope pegs for railway, canal or highway embank- 

 ments or excavations by the usual method of trial, several approxi- 

 mate calculations have to be made before the exact position of the 

 peg can be found. The labor itself is not difficult, but the time 

 required is such that, if the work is done faithfully, not over about 

 50 stations per day can be accomplished. Allowing for intermedi- 

 rtes and grade points, this is equal to about half a mile. Single 

 cuts or fills are occasionally of this length. 



By employing this special mechanical adaptation of the auxil- 

 iary telescope, as introduced by us in 1912, it is only necessary to 

 put in guide pegs at the center and termini of a fill or a cut, and 

 range all intermediate pegs without physical or mental exertion as 

 fast as the axe-man may be able to set them. 



Refering to the profile, set guide stakes at A, D and G by the 

 usual trial method, using the telescope bubble of the theodolite. 

 Place the instrument back on the hillside squarely behind the central 



