624 SEC. 15. GEOGRAPHY. 



only those on the reflecting circle, and on the universal instrument, were made 

 with the exhibitor's new machinery. 



The circles on both these instruments have no errors which could be detri- 

 mental, or which can be ascertained by the instruments themselves, since the 

 exhibitor's dividing machine (of 90 cm. diameter) is only arranged for copying, 

 and the normal-division itself being correct as far as 1 -2 seconds. 



The horizontal circle on the theodolite can be turned, and is provided with 

 a contrivance for centering; the iionii indicate at a division of 10 to 10 

 minutes 10 seconds. Those on the altitude circle indicate at a division of 

 20 to 20 minutes 30 seconds. 



3061. Ten-inch reflecting Prismatic Circle, similar to 

 that of Pistor-Martin. Julius fVanschqff, Berlin. 



3062. Universal Instrument with eight-inch Circles, 



and microscopical reading ; folding mechanism. 



Julius Wanschajf, Berlin. 



The drums on the universal instrument indicate direct four seconds, but 

 they have only figures of half the value, in order to have at once the mean 

 in measurements by the addition of the two readings of the oppositely situated 

 microscopes. 



By using the reversing mechanism, the handle of the same must be held 

 very firmly, especially by the replacement in the sockets. 



3063. Levelling Instrument with telescope of 15" focal 

 distance, 1 6" aperture ; a so-called compensation plane with 

 rotating level. A. Ott and G. Coradi, Kempten. 



This " compensation level " is a levelling instrument with telescope, which 

 can be turned round its optical axis and reversed in its sockets. The water 

 level is firmly fixed to the telescope, and can be turned in plumber blocks 

 round its own axis in such a manner that at a revolution of the telescope of 

 180 the scale of the water-level can, in the two reversed positions of the 

 same, be always turned upwards. 



The object of this arrangement -is to render one's self independent of the 

 errors occurring by damage of the telescope rings, and to give to the engineer 

 at all times the possibility of correcting the instrument as easily from any 

 position as in a levelling instrument with reversible telescope, with exactly 

 equal ring diameters and fixable water-level. By this arrangement the 

 tedious reversing of the telescope and the adjusting of the water-level, which 

 easily give rise to injury, will be rendered superfluous. Other constructors 

 have endeavoured to obtain this result by the employment of double-cut 

 water-levels ; a correct construction, however, of such instruments is very 

 difficult, and any errors occurring cannot be corrected. 



3064. Iron Levelling Staff, Reflector, and box level, 

 angle mirror, and hydrostatic balance in case. 



Zimmer BrotJiers, Stuttgart. 



This instrument, cross-disc, with iron bar, angular mirror, and water-level 

 in a box, serves for marking right angles and drawing perpendiculars. The 

 same is so far new that it is made entirely of metal ; on stony ground or in 

 frosty weather it is preferable to the cross-disc with wooden pole. 



3065. Reflecting Hypsometer. 



Zimmer Brothers, Stuttgart. 



