146 TRANSACTIONS OF THE [APR. 21, 



optical preparations of crystals of quartz, plates four inches long 

 and about one-one-hundredth of a millimetre in thickness, which 

 had been cut parallel to the rhombohedral face. These, when 

 punctured with a needle or sharp point, would alwa3's separate 

 into perfect rhombohedrons, showing that quartz, when properly 

 prepared, has as perfect a cleavage as any species. Mineralogi- 

 cal and j)etrographical microscopes were shown by MM. Nachet 

 and Bertrand ; goniometers by Fuess ; the goniometers of Mal- 

 lard and Wyrouboff, manufactured by Lutz ; and the Dufet ap- 

 paratus for measuring the angle of optical axes, manufactured 

 by Ducretet. 



In the centre of the French Jewelry Section, Class 37, was 

 exhibited the Imperial or Victoria diamond already described ; 

 at one of the four central corners, by Bapst & Falize, the his- 

 toric Sancy diamond, weighing forty-one carats ; opposite, a neck- 

 lace composed of pink, blue, yellow, brown, black, and other 

 colored diamonds. This section contained an immense number 

 of fine and curious diamonds, rubies, emeralds, and other pre- 

 cious stones, as well as several interesting lapidary exhibits, and 

 nearly fifty exhibits of imitation stones of all kinds, imitation 

 pearls, etc. A carved diamond turtle and fly, and some curi- 

 ously drilled diamonds, were of more than ordinary interest. 



At the Exposition there were three exhibits at which the 

 branches of cutting and polishing were carried on. At the Hol- 

 land pavilion the display made by Boas, of Amsterdam, had a 

 number of polishing wheels, the motive power of which was 

 steam, as well as a machine reconstructed, showing the manner 

 in which man-power was utilized during the eighteenth century. 

 With this exhibit there was a large series illustrating the vari- 

 ous forms of cutting the brilliant, rose, and table, as well as all 

 the forms of rough diamonds, such as cleavages, splints, those 

 for glass-cutting, and shaped for specially adapted tools. 



Two Belgians exhibited diamonds, — one, M. Latinie, a perfect 

 yellow octahedral diamond, weighing three hundred carats ; a dia- 

 mond cross cut from a single stone (which is not unique, as 

 claimed by the exhibitor, for such a stone was contained in the 

 Hope Collection, and was illustrated in the Hope Catalogue of 

 1839) ; some fanciful and curiously cut brilliants ; a small sword 

 cut out of three diamonds ; and the name of the exhibitor in 

 table diamonds, seventeen of which were nearly an inch in 

 length. 



In the main aisle Coutermans, of Antwerp, had an exhibit 

 with the polishing wheels, a series of the diamonds in the altered 

 kimberlite, and a black diamond, weighing thirty carats, which 

 it was reported had been purchased by the Shah, but of which 

 in reality he only inquired the price. 



