Of the many devices intended to hold bits in the stock, we have seen none that seems better adapted to serve the pur- j pose than that illustrated in the accompanying engravings. It is simple, durable, and perfectly reliable, holding the bit so firmly that its shank would probably break in an attempt to draw it by main force from the stock. Fig. 1 is a section of the holder with a bit in the socket, and Fig. 2 is a section showing the form of the pin which locks the bit in the socket, and the manner in which it is held by the spring. A, Fig. 1, is the portion of the bit filling the socket of the bit holder. A semi-cylindrieal concavity is cut in the holder, and another to correspond in the bit. These two concavities form, when the bit is entered, a hole in which plays the key-pin, B. This key-pin is attached to a spring, D, its normal position being that shown in Fig. 2. A portion of the key-pin is cut away at C forming a recess in the side of the pin, the length of which corresponds to the width of the socket. When the pin is pressed inward this recess is brought to coincide with .the socket, and a bit may either be withdrawn or inserted. When the pressure is removed from the head of the pin the spring withdraws it, so that its unrecessed portion fits both the concave recess in the socket and that in the bit, and the bit is firmly secured. A shoulder in the pin next the spring prevents it from being pressed in too far. Patented through the Scientific American Patent Agency, September 21, 1869, by Jacob Winkelhouse, who may be addressed, care of Dr. Hudson, 696 Broadway, New York city, tor further information.