380 Miscellanpowi Intelligence. 



Bulletin Technologique, this is an electro-magnetical phenomenon.— 

 N. M. Mag. xii. 446. 



3. Lapidarifs Wheel used in the East Indies for Catting Precious 

 Stones. — The following description is by M. L. de la Tour. This 

 kind of lapidaries' wheel is called, in the Tarmoule language, cou- 

 roundum-sane. It is composed of corundum, more or less finely 

 powdered, cemented together by lac resin ; the proportion by volume 

 is two-thirds powdered corundum, one-third lac resin. The corun- 

 dum powder is put into an earthen vessel, and heated over a clear 

 fire; when of a sufficient heat, which is the case when a small piece 

 of the resin readily fuses, the resin is added in portions, stirring at 

 the time to form^an intimate mixture. When made into a paste, it 

 is put on to a smooth slab of stone, and kneaded by being beaten 

 with a pestle; it is then rolled on a stick, re-heated several times, 

 continually kneading it until the mixture is perfectly uniform. It is 

 then separated from the stick, laid again on llie stone table, which 

 has been previously covered with very fine corundum powder, and 

 flattened into the form of a wheel, by an iron rolling-pin. The wheel 

 is then polished by a plate of iron and corundum powder; and, 

 finally, a hole is made through the middle, by a heated rod of 

 copper or iron. 



These wheels arc made of a grain more or less fine ; the coarser 

 perform the first rough work, and the finer cut the stones. They 

 are mounted on a horizontal axis; and the workman sitting on the 

 ground, makes them revolve with a spring-bow, which he moves 

 with his right hand, at the same time, with his left, holding the 

 stone against the wheel ; the latter being from time to time carefully 

 moistened and powdered with corundum powder. The polish is 

 given by wheels of lead and very fine corundum powder. 



It is supposed that this kind of lapidary's wheel may be imitated 

 with advantage in Europe ; the powder of emerald or diamond 

 being used in place of that of corundum. — Mem. du Museum. 

 ii. 230. 



4. On a New Piece of Artillery. — A report was read on the subject 

 of the experiments made at Brest, on the effects of the new kind of 

 artillery, proposed by M. Paixham. The piece {canon <J bombes) of 

 which trial was made, had a bore eight inches in diameter. The 

 object fired at was an old vessel of eighty guns ; each discharge 

 caused such injury as would entirely have disabled it from con- 

 tinuing in action. The fire of the new piece, charged with ten 

 pounds of powder, was much superior to that of a thirty-six pounder 

 ihaving a charge of twelve pounds of powder, at similar angles. The 

 commission was unanimous on the advantages which would be pro- 

 duced by the adoption of this new piece of artillery in the defence 

 of places, and in floating-batteries placed at the entrance of bar 



