9 



32. Nets for the construction of the models, No. 31. 

 9 sheets. Published by Thos. Murby. 



1876. Exhibited by J. B. Jordan. 



Gr. Miscellaneous Models, fyc. 



33. Models of natural crystals of diamonds. 



1877. Exhibited by the late E. Damon. 



12 glass models in a case. 



34. Models of the most celebrated precious stones. 

 1877. Exhibited by the late R. Damon. 

 28 glass models in a case. 



35. Models to illustrate the colours of various gems. 

 As used in Austrian schools. 



1882. Exhibited by E. J. Gehlsen $ Co. 



24 coloured glass models, cut in rose form, in a box. 



2. INSTRUMENTS USED IN MINERALOGICAL AND GEOLOGICAL 



KESEARCHES. 



A. Goniometers. 



36. Large goniometer and spectrometer, with heating 

 apparatus to allow of the examination of crystals at high 

 temperatures, and case of accessory apparatus. 



E. 84. 1885. Made by R. Fuess, Berlin. 



This instrument is arranged for the observation of the angles 

 of crystals with extreme accuracy, and the changes they 

 undergo with changes of temperature. 



It consists of a tripod, with three levelling screws, the centre 

 of which is perforated and encloses a vertical cylinder, which 

 supports at the top a horizontal divided circle, which can 

 be rotated by means of the large screw beneath the table 

 of the tripod, or by another large parallel screw below, 

 which is bound to the first by upright bars. The fine adjust- 

 ment is effected by a tangential screw on an arm projecting 

 from beneath the tripod table, and it is clamped in position by a 

 radial screw on the same arm. Through the centre of this 

 cylinder passes a smaller cylinder, independent of the first, and 

 carrying the central support. This can be rotated by the 

 uppermost of the smaller screws beneath the tripod table, which 



