The main top board M, Fig. 2, may be either made from one piece of 2 by 12-in. plank, 3-1/2 ft. long, or made up of 14 strips of maple, 7/8 in. thick by 2 in. wide and 3-1/2 ft. long, set on edge, each strip glued and screwed to its neighbor.  When building up a top like this be careful to put the strips together with the grain running in the same direction so the top may be planed smooth.  The back board N is the same length as the main top board M, 8-1/2 in. wide and only 7/8 in. thick, which is fitted into a 1/2/-in. rabbet int back of the board M. Thes boards form the top of the bench, and are fastened to the top pieces of the supports with long screws.  The board E is 10 in. wide and nailed to the back of the bench.  On top of this board and at right angles with it is fastened a 2-1/2-in. board, F. These two boards are 7/8 in. thick and 3-1/2 ft. long.  Holes are bored or notches are cut in the projecting board, F, to hold tools.

Details of the vise are shown in Fig. 3, which is composed of a 2 by 6-in. block 12 in. long, into which is fastened an iron bench screw, S. Two guide rails, GG, 7/8 by 1-1/2 in. and 20 in. long, are fastened into mortises of the block as shown at KK, and they slide in corresponding mortises in a piece of 2 by 4-in. pine bolted to the under side of the main top board as shown at L. The bench screw nut is fastened in the 2 by 4-in. piece, L, between the two mortised holes.  This piece, L, is securely nailed to one of the top cross pieces, C, of the supports and to a piece of 2 by 4-in. pine, P, that is bolted to the under sides of the top boards at the end of the bench.  The bolts and the bench screw can be purchased from any hardware store for less than one dollar.

** Forming Coils to Make Flexible Wire Connections [443]

When connections are made to bells and batteries with small copper wires covered with cotton or silk, it is necessary to have a coil in a short piece of the line to make it flexible.  A good way to do this is to provide a short rod about 3/16 in. in diameter cut with a slit in one end to hold the wire and a loop made on the other end to turn with the fingers.  The end of the wire is

[Illustration:  Forming Wire Coils]

placed in the slit and the coil made around the rod by turning with the loop end.

** Photographing the North Star [443]

The earth revolving as upon an axis is inclined in such a position that it points toward the North Star.  To an observer in the northern hemisphere the effect is the same as if the heavens revolved with the North star as a center.  A plate exposed in a camera which is pointed toward that part of the sky on a clear night records that effect in a striking manner.  The accompanying illustration is from a photograph taken with an exposure of about three hours, and the trace of the stars shown on the plate by a series of concentric circles are due to the rotation of the earth.