II. MINING. 873 



inclined for the purpose of taking a sight in steep mines. When the semi-circle 

 is not required, it is simply folded down on the outside of the compass-box. 

 In practice this is found to be an exceedingly convenient arrangement. 



339Ob. 12-inch Circular Protractor, divided to 15 minutes 

 for plotting in connexion with the dial. Joseph Casartelli. 



339Oc. German Compass, which has been used for a great 

 number of years in the different operations, made at the mines of 

 Almaden. Royal School of Mines, Madrid. 



3390d. 5-inch Miners' Compass. G. W. Strawson. 



3390e. 2 {-inch Miners' Compass with folding sights. 



G. W. Strawson. 



3391. Mining Compass, with arrangement for suspending 

 needle 7 cm. long, circle graduated in degrees. 



A. and R. Hahn, Casscl. 



3392. W. Konig's Telescope Mining Compass, with 

 level and graduated arc, together with Horold's centre foot-plate 

 in box with lock. 



Royal Prussian Upper Mining Court for the Provinces of 

 Silesia, Posen, and Prussia (Breslau). 



This instrument is used by mine surveyors, and at official revisions of 

 mine surveys. 



3394. Steel Measuring Tape for mining surveyors, in 

 case. C. Osterland, Freiberg. 



To be used principally in conjunction with a mine theodolite constructed 

 by the exhibitor. 



3395. Head with screw for the steel tape. 



C. Osterland, Freiberg. 



3396. Travelling Box Compass, with brass support adapted 

 for levelling with a small suspending apparatus, graduated arc, and 

 appurtenances. C. Osterland, Freiberg. 



Constructed for travellers in thinly populated countries, and is adapted for 

 attaching to the saddle. 



3397. Mine Surveying Instrument, consisting of compass, 

 suspending apparatus, and protracting plate clinometer, and two 

 cases. A. Lingke and Co., Freiberg, Saxony. 



3397a. Henderson's Hypo-thonite, with stand, is an im- 

 proved form of the same kind of instrument generally in use for 

 rough surveying, especially in underground workings of collieries 

 and other mines. Ridley Henderson. 



The improvements are additions to the ordinary Miner's Dial or Circum- 

 ferentor, viz. : 1st, a radiating limb and sights worked by rack and pinion 

 attached to a quadrant, for taking vertical angles. 2nd, a similar arrange- 



