170 



Mining Transit. 



Interchangeable with Lamp Targets* above Lereling Screws. 



The leading features possessed by this instrument, as made by us, are, that it can 

 de interchanged with the lamp targets above the leveling screws (see opposite page) so 

 that after they have been set up their relative position as to height and location will 

 remain exactly the same upon being transferred from one tripoa to another. It is an 

 instrument especially adapted to the work of an engineer in mines, and as such 

 involves a great deal of apparatus not possessed by instruments intended for surface 

 work. Viewed in its entirety, as a surveying instrument, it is more complicated to 

 handle than the more customary styles, and with the attachment oi a side or top 

 telescope it grows still more so, and is then difficult to manage in cramped places. 

 The advantages derived from its use may, however, compensate for the more cumber- 

 some features of this instrument. Two lamp targets are commonly suppJed with ;i n 

 instrument of this kind, but frequently one only is ordered, according to the character 

 of the work for which it is intended. The vertical centers of the lamp targets have to 

 be well fitted into the sockets of the leveling heads, and in consequence they cannot 

 be furnished separately. The engineer will therefore decide whether one or two lamp 

 targets are necessary for this work. The lamp targets are of the same height as the 

 transit measured from the base above the leveling screws to the line of sight, and each 

 is provided with two spirit levels. The targets can be revolved in the vertical and 

 horizontal planes. By means of a tubular sight, situated on top of the target, the 

 latter can be readily set in the direction of the instrument so tha' its face will lie at 

 right angles to the line of sight. The lamps can be raised or lowered at will, and can 

 be detached whenever necessary. It is of the bull's-eye pattern ; and the best lard-oil 

 only should be burned in it. A disc of milk glass placed between it and the target 

 furnishes an illuminated background, agaicst which the intersection and outlines 

 of the target are seen sharply defined,, 



f Weight of Mining Transit No. 7, about 1 1 Ibs. 



, I one lamp, " 6} " 



-j Mahogany box containing instrument and one lamp, targei etc., about 32 " 



one Extension Tripod, about 9! Ibs. ; two Tripods^ . . . " 19 " 



i Gross weight of this instrument, complete, packed securely for shipment in two boxes, about 70 lb. 



f Weight of Mahogany box, containing instrument only, r.bcv t .... 22 Ibs. 



J " 2 lamps, targets, etc.. * : .'.... 26 " 



1 three Tripods, " 2 8j " 



[ Gross weight of instrument, complete, packed securely for shipment in 3 boxes, . . about 120 Ibs. 



No. 7. Mining Transit, size as in No. 6,t with one lamp target as shown on 

 opposite page ; graduations on solid silver, verniers reading to minutes, are provided 

 with ground glass shades; 5 inch full vertical circle; spirit level, clamp and 

 gradienter screw to telescope ; illuminator shade ; striding level and fixed stadia wires, 

 2 extension tripods, two plumb-bobs P etc. Lamp target packed in Instrument-box, 



Price, $38O.OO 



No. 7a. Mining" Transitp as above, but with 2 lamp targets, both packed in 

 separate box, three extension tripods, 3 plumb- bobs, etc. 



Price, $46O.OO 



instruments No. 7 and 7a 9 without Striding Level, less .... $20.00 



Gradienter, " .... 5.00 



" " " Fixed Stadia Wires, less . . . 3.00 



For price of extra attachments, see Extras to Mining Transits, page 162. 



NOTE. To interchange the instrument and the lamp target proceed as follows : First withdraw the spring 

 bolt of the lower clamp for the outer center by means of the small milled-heacled nut at the end of the clamp opposite 

 the tangent-screw. Then loosen the clamp screw immediately above the leveling head. Now upon pulling back 

 the spring bolt, situated at the side of the clamp, the instrument or the lamp can be detached by lifting it out of the 

 socket in the leveling head. These sockets as well as the clamps, which serve to fasten the instrument or lamp 

 target to the leveling head, should be kept free from dirt or grit. After clamping the instrument to the levdini; 

 head, to prevent any motion in its socket, and then releasing the small milled-headed nut from its fastening on the 

 spring bolt of the lower tangent-screw, the transit is ready icr work and can be manipulated the same as other 

 instruments of our construction. 



** The difference existing between the lamp target anc". the Jamp formerly furnished with our Mining Transit 

 No. 7, consists in, that in the latter the flame of a parr.ffine candle, kept at the same height ;s the instrument, 

 was to be sighted at, which of course was a source of inaccuracy, particularly for short sights. I'.y using the 

 'iamp target shown on the opposite page, either long or shcrt sights can be taken with rapidity and accuracy. 



Customary size of instrument on account of its lightness, as compared with NO. 5, hut for exceptional uses 

 we are prepared to furnish this style of instrument cf size No. 5 whenever desired, but its si/c and xreatT weight 

 about 4 Ibs. more for the instrument and about .- ).b. more for each lamp target and tripod, etc. makes it, 

 however, very unwieldy in cramped places. 



