The Atlantic Telegraph Cable.—John Bull in a Fit of Mulligrubs

1858 Scientific American  
These useful tools are essential to the oper ations of almost every branch of mechanism. They are necessary agents in the fab rication of the most delicate watch work, mathemati cal instruments, steam engines, printing presses, houses, and shi ps. As a consequence vast quanti ties of them are required in every department of industry, and to supply the de mand they are manufactured extensively in various parts of our country, and a very large number are annually imported. Files are made of the
more » ... st English cast steel. The rods for the blanks are obtained of such sizes as are suited to the character of the files to be furnished. The first operation is that of forging the blanks from the rods. This is done by blacksmiths who must be very skillful, quick, and exact workmen, as the metal must not be heated above blood-red temperature. All the blanks for each size of file must be exact in length and swedged to the proper shape, after which the tangs are forged. The next operation is that of anneal ing them, to render them soft and ductile. This is done by putting them into an anneal ing oven, or placing them in a box protected from the air by being buried in sand, then heating them to a red heat, and cooling slow ly. After tl is they are ground to a smooth face, and are ready for cutting. The burring
doi:10.1038/scientificamerican09251858-22a fatcat:gyrn5yt5erah5nb5ccn2sx6lle