746 SEC. 17. MINERALOGY, CRYSTALLOGRAPHY, ETC. 



A reflecting goniometer of the most perfect and improved construction. 

 The circle is vertical, with a scale of 1 6 degrees in silver, the vernier giving 

 readings to 10'. Diameter 21 centimeters, with lens, telescope, microscope, 

 illuminating tube with prism, and arrangement for centering the crystals ; 

 also a lens for the objective of the telescope, &c. On a marble slab. Property 

 of the K. K. Bergakademie of Leoben, in Styria. 



3445. E. Mitscherlich's Goniometer. 



Prof. A.. Mitscherlichy Miinden^ Hanover. 



A description of the goniometer is given in the memoir in " Berichte der 

 konigl. preussischen Akademie der Wissenschaften, 1873." E. Mitscherlich 

 used this goniometer in much of his crystallographic work. 



3446. Goniometer (made by Messrs. Powell and Lealand), 

 with adjustments for mounting a crystal (as described in the in- 

 troduction) ', and with fittings adapting it for the purposes, 1, of 

 an instrument for determining refractive indices, and 2, for mea- 

 suring the angle between the optic axes of biaxial crystals. 



Prof. N. S. Maskelyne. 



3446a. Goniometer, according to Borsch's principles; exe- 

 cuted by Breithaupt and Son. 



High School for Industry at Cassel (Dr. E. Gerland). 



The goniometer a deflecting goniometer, according to Babiuet can be 

 altered into a spectrometer by affixing a prism. It has the advantage that all 

 examinations and corrections on it can be effected without special auxiliary 

 means, as well as all angles ; refraction coefficients can be found by two 

 entirely different methods. (See Borsch, Poggend. Ann., vol. CXXIX., p. 384.) 



3447. Polarising Apparatus, with telescope tube and goni- 

 ometer. Wilhelm Steeg, Hamburg, Prussia. 



3448. Brezina's Stauroscope. 



Wilhelm Steeg, Hamburg. 



3449. F. Groth's Universal Apparatus for Crystallo- 

 graphic Optical research. R. Fuess, Berlin. 



Vide " Physikalische Kry stall ographie/' by Professor P. Groth, Leipzig, 

 Engelmann, 1876. 



3450. ** Microgoniometer," for measuring with the micro- 

 scope. Prof. Friedrich Pfaff, Erlangen. 



The arc which stands horizontally can also be placed so that it can be 

 used for vertical measurements. A small pamphlet on the instrument 

 accompanies it. 



3451. Charles' original Goniometer. 



Conservatoire des Arts et Metiers, Paris. 



3453. Apparatus for studying and exhibiting the 

 Optical Characters of Crystals. 



