744 SEC. 15. GEOGRAPHY. 



only those on the reflecting circle, and on the universal instrument/Vere 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 verniers 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. 



3062. Universal Instrument with eight-inch Circles, 



and reading microscope. Julius Wanschaff, Berlin. 



The circles on the universal instrument read to four seconds, But they 

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

 the addition of the two readings of the opposite microscopes. 



3O66. Small Universal Instrument for measuring heights, 

 &c., with stand. Zimmer Brothers, Stuttgart. 



Small levelling instrument and theodolite in one, for measuring heights, 

 horizontal angles, &c., and for levelling, and setting outright angles. Useful 

 to foresters and agriculturists, on account of its cheapness, and capability of 

 being easily handled. 



3073. Theodolite with two Vertical Circles. 



Geodetic Institute of the Royal Polytechnic School, 

 Munich, Prof. Dr. von Bauernfeind. 



This instrument was made by Ertel & San, of Munich, from the exhibitor's 

 design, and is suited for investigations as to the relative value of the vernier 

 and microscope readings of five divisions, and, secondly, for observations upon 

 the magnitude of terrestrial refractions and their variation with temperature 

 and the pressure of the air. The exhibitor has not yet described the instru- 

 ment, because the number of observations made with it is still too small to 

 allow certain results to be deduced from them. The instrument, however, 

 perfectly fulfils its purpose. 



3074. Repeating Theodolite, with 15cm. horizontal circle, 

 and 12 cm. covered altitude circle. A. Bonsack, Berlin. 



Both circles are divided on silver ; the first to 20' with two verniers 

 reading to half minutes ; the second to 30' reading to one minute by one 

 vernier. The telescope is adapted for distance measurements by a method 

 invented by the exhibitor, and which has been strongly recommended by 

 Herr S. Woyike, who used it in operations on the Ostbahn. 



3075. Theodolite with Micrometers on the horizontal 

 circle. F. W. Breithaupt and Son, Cassel. 



Theodolite for Geodetic purposes. Horizontal circle 20 centimetres in 

 diameter, with two graduations, the coarse to 20', the fine to 5', reading by 

 micrometers, to two seconds directly ; the fine division is protected by a cover ; 

 the verniers of the vertical circle show 10 seconds ; orthoscopic telescope for 

 transit (Durchscftlagen) and reversal in the Y's with arrangement for 

 distance-measurement, reversing spirit-level and level on the tube of the tele- 

 scope. The microscopes have parallels and reversion scales on glass. This 

 theodolite belongs to the Royal Forest Academy at Miinden. 



