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Art. XII.— MISCELLANEOUS INTELLIGENCE. 



I. Mechanical Science. 



1. Cutting of Steel by Soft Iron. — Mr. Barnes, of Cornwall, Con- 

 necticut, has ascertained a singular property of soft iron in cutting hard 

 steel. He had fixed a circular plate of soft sheet iron on an axis, 

 and putting it into a lathe, gave it very rapid rotatory motion, apply- 

 ing, at the same time, a file to it to make it perfectly round and 

 smooth ; the file, however, was cut in two by the plate, the latter 

 remaining untouched; and it was found not to have been much 

 warmed in the operation, though a band of intense fire surrounded it 

 whilst in action. 



A saw made of a very hard plate, which required altering, was cut 

 through longitudinally in a few minutes, and afterwards teeth were 

 cut in it by the same means. Had the file been used to produce the 

 same effect, it would have required a long and tedious operation. 



Rock crystal applied to the plate cut it readily. 



Mr. Perkins, of Fleet-street, has verified this remarkable and useful 

 observation. A piece of a large hard file was cut by him into deep notches 

 at the end, where, also, from the heat produced by friction, it had 

 softened and been thrown out like a burr. On another part of the 

 file, where the plate had been applied against its flat face, the teeth 

 were removed, without any sensible elevation of the temperature of 

 the metal. The plate, which had previously been made true, was 

 not reduced either in size or weight during the experiment, but it had, 

 according to Mr. Perkins, acquired an exceeding hard surface at the 

 cutting part. — Sillimaris Jour. vi. 336*. 



2. Water-proof Cloth. — A chemist of Glasgow has discovered a 

 simple and efficacious method of rendering woollen, silk, or cotton 

 cloth completely water-proof. The mode adopted is to dissolve 

 caoutchouc in coal tar oil, produced in abundance at the gas works; 

 by a brush to put five or six coatings of this mixture on the side of 

 the cloth or silk on which another piece is laid, and the whole passed 

 between two rollers. The adhesion is most complete, so much so, 

 that it is easier to tear the cloth than to separate it from the caout- 

 chouc. 



3. Chain Bridge over the Tamar. — A chain or suspension bridge 

 across the Tamar, at Saltash, in Devonshire, is now seriously in- 

 tended ; and the wealthy landholders in Devon and Cornwall have 

 readily come forward with offers of pecuniary assistance. It is to be 

 of sufficient height to admit of frigates passing under without striking 

 their jury masts. Such a bridge would be of great importance to that 

 part of the country, for the numerous advantages it would confer. 



