886 6EC. 17. MINERALOGY, CRYSTALLOGRAPHY, ETC. . 



3439a. Simple Substitute for a Goniometer. 



Prof. W. H. Miller, M.A., F.R.S. 



By means of this a crystal can be measured by Wollaston's method, and 

 the angle of an edge determined by measuring the angle between two lines 

 drawn on paper along the wooden part of the instrument in its two different 

 positions, by comparing the arc, intercepted by the two lines on a circle 

 drawn through the point of intersection of the lines, with the whole circum- 

 ference, by means of compasses. 



3440. Goniometer 9 with additional pieces of apparatus, by 

 which it may be converted into an instrument for determining 

 refractive indices, and an instrument for measuring the angle 

 between the optic axes of biaxial crystals. 



University of Oxford. 



3441. Contact Goniometer, being the instrument used by 

 the Abbe Haiiy. University of Oxford. 



It was formerly in the collection of Haiiy's minerals, acquired by the late 

 Duke of Buckingham. His Grace presented it to Dr. Buckland, by whom 

 it was placed with the collection of minerals belonging to the University of 

 Oxford, in which Dean Buckland was professor of mineralogy and geology. 

 The Dean's autograph is on the morocco case. 



3442. Goniometer, with horizontal circles, and adjusting level. 



Prof. Baron von Feilitzsch, Greifswald. 



This reflective goniometer has a dividing circle of 7*5 inch diameter. 

 The division runs direct as far as ^, and with the application of the vernier 

 5 minutes may be read. The instrument can likewise be used for spectrum 

 experiments. 



3443. Goniometer. R. Fuess, Berlin. 

 3443a. Goniometer. M. Lutz, Paris. 

 3443b. Goniometer, Wollaston's. M. Lutz, Paris. 

 3443 c. Goniometer, Babinet's. M. Lutz, Paris. 



3444. Reflecting Goniometer, on marble slab, in maho- 

 gany case. F. W. Breithaupt and Son (G. Breithaupi), CasseL 



A reflecting goniometer of the most perfect and improved construction. 

 The circle is 21 centimeters in diameter, divided on silver to 10', the vernier 

 giving readings to 10", with lens, telescope, microscope, illuminating tube 

 with prism, and arrangement for centering the ciystals ; 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. Mitscherlich, Miinden, Hanover, 



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

 konigl. preussischen Akademie der Wissenschaften, 1843." E. Mitscherlich 

 used this goniometer in much of his crystallographic work. 



