The accompanying illustration shows a new device made by the New Britain Machine Company, New Britain, Conn., for the hand filing of band saws. It consists of a specially designed automatically-closing vise and of a roller guide which is attached to the end of the file. It is claimed by many that a band saw properly hand-filed cuts better than a machine-filed saw. Hand filing is an art that can only be acquired by constant practice and long experience. The greatest difficulty in hand filing is to give to all the teeth the same shape and to hold the file in a vertical position. The New Britain band saw filer obviates the above difficulty, inasmuch as the file is guided mechanically in the horizontal direction and is also prevented from turning by means of the roller guide which is at-tashed to the end of the file. The file, by means of this guide, can be set to any angle and thus the contour of the saw teeth can be maintained uniform throughout the saw. The vise is fitted with a spring which regulates the pressure of its jaws on the saw. When filing, the tension of the jaws on the saw is ample to hold it firmly and to prevent it from chattering, and yet it allows the saw to feed along by a slight pressure of the file from left to right, as a pressure in this direction tends to release the jaws enough to allow the saw to slip, and when the pressure is removed the saw is firmly held, as above noted. This free feeding feature is regulated by a stop pin at the right of the fixed jaw which prevents the over-running of the file when sharpening or feeding. By moving the lever shown at the right of the vise the saw can be easily released when desired.
German papers state that it is a well-known fact that the presence of very small quantities of foreign sub-stances is likely to change the qualities of metals and their alloys materially. Gold is no exception to this rule. Admixture with foreign substances often makes it brittle, while otherwise it is the most malleable and ductile among the metals. Even if alloyed with pure copper, gold shows these undesirable qualities, and such an alloy cannot be used for the manufacture of jewelry, for the coining of metals, or for other industrial purposes.