III. MISCELLANEOUS. 637 



3112a. A 12-inch Level mounted on the Ball move- 

 ment. H. Husbands, Bristol. 



The 12-inch level is mounted on the ball arrangement, the combined inven- 

 tion of Mr. Metford and Mr. Fronde. 



3113. Levelling Instrument with Telescope 40 cm. long, 

 arranged for folding down and turning in its sockets, with stand. 



A. Bonsack, Berlin. 



The bearers are closed by springs. The horizontal circle is divided on 

 silver to |, and adapted for reading to one minute. 



3114. Compensation Level. 



./. W. Brcithaupt and Son, CasscL 



A portable instrument. It possesses the important advantage, that, with 

 it, without previous correction, we may level correctly, even if the telescope- 

 cylinders are unequal, provided that the spirit-level is correctly adjusted, 

 which may be easily ascertained by turning it round in its points of sus- 

 pension. By means of the tangential screw the spirit-level is brought to 

 equilibrium in both positions of the telescope, and the mean of the two read- 

 ings is taken. By this operation all errors are compensated. The divided 

 head of the tangential screw serves at the same time for distance-measuring ; 

 and, besides, a distance measure on glass is inseited in the eye-piece of the 

 telescope for direct measurement. 



3115. Reflecting Circle, according to Pistor and Martins. 



J. W. Brcithaupt and Son, CasscL 



3115a. Improved Reflecting Circle of Fister and Mar- 

 tins. The Pulkowa Observatory. 



A full description of the patent reflecting circle of Pister and Martins in its 

 original construction is given by the inventors in the Astronornische Naehrich- 

 ter, vol. xxiii. In the exhibited form general improvements are introduced by 

 the inventors on Professor Dallen's suggestion ; for instance, all correction 

 screw? of the prisrna are removed, the stiffness of the main body is considerably 

 increased, the different parts of the instrument are more symmetrically dis- 

 posed, the telescope and the dark glasses are separated from the radius, on 

 which mirror and prism are fixed, means are given for cross observation to 

 the extent of 288, &c. Also.Sthe stand for observations on shore is in parts 

 changed and rendered more practical. 



3116. Precision Levelling Instrument, with telescope of 

 lo" focal distance, 16" aperture, a so-called Compensation 

 Level with turnable water-level, according to new patent con- 

 struction. A. Ott and G. Coradi, Kempten. 



3117. Levelling Instrument with horizontal circle. 



Imperial German Navy (August Lingke and Co.). 



3118. Large Levelling Instrument, with folding down 

 telescope and fixed ether-level; above it a reflector, the objective 

 35 mm. aperture, and 4o cm. focal distance. 



A. Frerk and Son, Hanover. 



