



PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 939 



FiRE-PKooF Wood. 

 Dr. Feiichtwanger stated that a very good fire proof wood 

 could be made by soaking the wood in lime water and then coat- 

 ing it with silicate of soda. 



New Iron. 

 Col. Edwin Henry exhil)ited a specimen of iron from Gi'een 

 county, near Greenville, Tennessee, manufactured by the New York 

 and East Tennessee Iron Company. It contains seven per cent of 

 manganese. This is what the Germans would call spikelcisen. 

 With three per cent of railroad scrap and the rest of this iron a 

 very good metal can be made. No iron ore like tliis, containing 

 manganese, has been found in this country except the deposit of 

 the N. J. Franklinite. It differs from the latter in containing no 

 traces of zinc. 



Water Meter. 

 Mr. James Cochran exhibited his water meter, and put it in 

 practical operation. The Avater is discharged into a tilting pan 

 which is emptied as soon as full, and each motion of the pan moves 

 an index so that the actual quantity is measured. The inventor 

 claims that by an improvement lately made the Avater passing 

 through his meter is properly aerated l^efore it is delivered. 



Submarine Cables. 

 Samuel C. Bishop presented a paper on the art of telegraph 

 insulation and on submarine cables insulated with gutta percha. 

 He also exhibited a sample of pure gutta percha insulated wire, 

 being a piece of one of the earliest submarine cables ever made 

 in the world, and which was laid across the North river in 1849, 

 and this piece taken up from the shore under ground, in 1858. 

 When taken up was in a perfectly sound condition. It is now 

 (eight years after) cracked on outside from being exposed to the 

 atmosphere only. Many other submarine wires had been taken 

 up and examined by Mr. Bishop during an experience of eighteen 

 years, and he stated that in every case the gutta percha was found 

 to be sound and perfect. He also exhibited a piece of pipe made 

 in 1851 (at the works under his charge) which was laid across the 

 East river to convey the Croton water to Blackwell's Island. This 

 piece was cut out when the pipe was taken up for repairs, and 

 relaid in. 186G, and is now as perfect as when made fifteen years 

 ago. He also exhibited a piece of submarine cable passed through 

 an iron weight with a hard pine wedge, to keep the wire in place, 



