I'M 



ENGINEERS DUMPY I-EVEL. 



A Leveling Instrument of I'ri-risioii. 



On acccnnt of the greater compactness, our dumpy level is best adapted for 

 railroads, water works and reconnoissance, etc., permitting of liMi aceunev bv 

 greater simplicity, and is less liable to derangement of all parts. As regards size 

 it has all the. advantages of the larger engineers' levels, but as it consists of a lesser 

 number of pieces and screws, is superior to these in point of durability and perma- 

 nency of adjustments. With a properly adjusted dumpy level of our make, (set 

 adjustment of dumpy level,} an engineer can perform as high a class of work as he 

 is generally enabled to do with a good wye level, depending, as he does, not so much 

 on mechanical perfections, as on his own superior skill and sense of accuracy in 

 making adjustments. The upper part of this instrument is entirely cloth-finished. 



The instrument is packed in a mahogany box, containing a sun-shade, a wrench, 

 a screw driver and adjusting pin. 



Weight of instrument lOlbs., weight of tripod from 7 to 1% Ibs. 



Gross weight of Instrument, packed securely for shipment, in 2 boxes, about 45 

 Ibs. 



Price $1OO.OO. 



CodeWord. 15 inch inverting telescope . . Abronia 



" 17^ " erecting telescope .... Aconite 



(For Extras such as stadia wires see below and for code words page B 

 of complete code at back). 



Extras to Engineers' Dumpy Level. 



Stadia Wires, fixed s:;.iio 



Gossamer waterproof bag, to protect the instrument in case of rain or dust, . 1.00 



Bottle of fine watch oil, to lubricate the level center, ..... 0.25 



It may not be amiss to explain the principal parts of this Dumpy Level. From the illustration 

 it will be seen that the mechanical parts are few and can easily be made to be mechanically correct, and that 

 there are no working strains whatever in the metal to exert an undue influence upon the adjustments with 

 changes of temperature. 



The telescope barrel and both uprights are cast in one piece of hard composition metal ; and in order to 

 arrive at a high degree of accuracy the barrel is bored out to be truly cylindrical, a condition never attained 

 by the use of drawn tube. (For reasons mentioned later both ends of the outside tube are slightly larger in 

 diameter, forming collars turned truly concentric to the bore, serving in principle the same object as collars 

 of a Wye Level telescope.) This being accomplished, the bottom surface of the uprights is then planed 

 parallel to the bore. The strongly ribbed cross-bar and instrument center are also cast in OIK- piece of hard 

 bell-metal. When the center about which the instrument revolves Is fitted the resting-places for the uprights 

 are then turned off so as to be truly at right angles, from which follows thnt the geometrical axis of the 

 telescope barrel when placed upon them must also be at right angles to the center. The level casing. to, is 

 a casting. The spirit level itself is fastened into this casing by a superior method t<> preclude any strain, so 

 that its true form may be preserved. The focussing slide is the only tube made of drawn brass turned and 

 closely fitted in the lathe. 



In adjusting this instrument in the shop it is treated like a Wye Level. The collars at the end of ti.e 

 telescope barrel serve to adjust the cross-wires for collimation by revolving the telescope in wyes. Tin 

 accomplished the telescope barrel with its attached level is then firmly screwed to the cross-bar. T! 

 step in the shop is to adjust the spirit level to the line of collimation as described elsewhere. This bring done 

 the adjuster in the shop now proves whether the geometric and optic axes of the telescope are really in the 

 horizontal plane bv revolving the instrument 1 80 on its center ; should the bubble remain in the midd; 

 tube it must be assumed that it is; however, if not, he touches one of the uprights off until i: 

 rule the mechanical work is so correct that the geometric and optic axes coincide- within a few division marks 

 of tlie graduated scale, requiring but a very few strokes with a fine file for final adjustment. 



From the foregoing it will be seen that a levelling instrument so constructed, barring severe accidents. 

 must hold its adjustments for years, and that all subsequent verifications of the line of coilim.uioii in the field 

 by the two ptg method must be made by the Kngine. r hv slightly moving the cross-wires, and that the adjust- 

 ment of the spirit level is to be made in the customary manner by simplv turning the instrument \^"" on its 

 center. An instrument so ( obstructed needs but little care and therefore is better adapted to rough n 

 whi< h it is iiaMe to he subjected at times, since its simplicity ensures greater freedom from derangement. 



The tic-sign of the annexed illustration of I >mnpv Level must therefore stand as an example of iiood 

 ' prefer it to an ordinary Wye Level. The prevailing mistrust can generally be 

 rcial articles of a similar kind. 



