PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 395 



tiircd, raw hide, prepared and shaped like the human \eg. It is very light 

 and strong. The knee joint is a double lap joint. The whole leg weighs 

 ■when finished, four pounds. The hide is first baked in an oven to take out 

 the surplus animal matter, and then receives several coats of paint. The 

 old way of fa.'itcning these limbs was by a strap over the shoulder, but 

 with this appendage a person having only an inch of stump can have it 

 fastened as firm as though the stump M-ere six inches in length. It is not 

 as heavy as a gutta percha limb ; there is probably not over three quarters 

 of a pound of wood in the whole. Instead of softening the skin, perspira- 

 tion made it harder. Willow wood is dispensed with in this leg. The cost 

 all complete is about one hundred dollars. 



Paper from "Wood. 



Dr. W. Rowell presented specimens of paper from wood made by Mr. 

 Antonio Meucci, of Staten Island, and explained the process of manufacture. 



It was stated that the process would be referred to the standing commit- 

 tee of manufactures science and art of the Institute, for a report. 



The Chairman presented the following interesting summary of scientific 

 news: 



A New Gas Engine. 



The Gazomoteur of M. Belon is in successful operation near Paris, and 

 has been favorably reported upon by the French Academy of Sciences. An 

 economy equal to 60 or TO per cent, is claimed for it. The principal parts 

 are an air-pump, a smoke consuming furnace and a motive cylinder. The 

 furnace, when the engine is at work, remains closed, except at the orifice 

 by which the air-pump opens on it and at the one by which the heated air 

 sets the cj'linder in motion. It is ao arranged that a quantity of combusti- 

 ble matter, equal to that which it consumes, falls constantly into it. A 

 state of combustion is kept up by the air-pump. Part of the air passing 

 from this rushes into the furnace, the rest combines with the coal-gas, 

 forming a gaseous mixture, the volume of which is far greater than that 

 of the air previous to its introduction into the furnace. This mixed air 

 acts on the piston with a force proportionate to the increased volume pro- 

 duced by the temperature. 



"V^ATER FOR Paris. 



Paris, at last, is to have a reservoir capable of supplying 40,000 cubic 

 feet of pure water every 24 hours. The water is to be brought from the 

 Marne. The coat of the work will be forty millions of francs. 



Specific Heat. 



Dr. Kopp has communicated to the Royal Society his important investi- 

 gations in this branch of science. An immense number of liquid and solid 

 bodies had been experimented upon, he arrived at the conclusion that each 

 element in the solid state, and at an adequate distance from its melting 

 point, has one specific or atomic heat; aud that for each element it is to be 

 assumed that it has essentially the same specific or atomic heat in the free 



