The spindle of the pointer swings freely between two bars of brass, G, 1/16 in. thick, 1/4 in. wide and 2-1/2 in. long.  A small hole is countersunk in one of the bars to receive one end of the spindle and a hole 1/8 in. in diameter is drilled in the other and a thumb nut taken from the binding-post of an old battery soldered over the hole so the screw will pass through when turned into the nut.  The end of the screw is countersunk to receive the other end of the spindle.  A lock nut is necessary to fasten the screw when proper adjustment is secured.  A hole is drilled in both ends of the bars for screws to fasten them in place.  The bar with the adjusting screw is fastened on the back so it can be readily adjusted through the hole H, bored in the back.  The pointer is bent so it will pass through the U-shaped cut-out and up back of the board B. A brass pin is driven in the board B to hold the pointer from dropping down too far to the left.  Place the tin, Fig. 4, so it will just clear the tin, Fig. 5, and fasten in place.  The magnet is next placed with the ends of the coil to the back and the top just clearing the tin strips.  Two binding screws are fitted to the bottom of the back and connected to the extending wires from the coil.

The instrument is now ready for calibrating.  This is done by connecting it in series with another standard ammeter which has the scale marked in known quantities.  In this series is also connected a variable resistance and a battery or some other source of current supply.  The resistance is now adjusted to show .5 ampere on the standard ammeter and the position of the pointer marked on the scale.  Change your resistance to all points and make the numbers until the entire scale is complete.

When the current flows through the coil, the two tinned strips of metal are magnetized, and being magnetized by the same lines of force they are both of the same polarity.  Like poles repel each other, and as the part Fig. 4 is not movable, the part carrying the pointer moves away.  The stronger the current, the greater the magnetism of the metal strips, and the farther apart they will be forced, showing a greater defection of the pointer. —­Contributed by George Heimroth, Richmond Hill, L. I.

** How to Make an Equatorial [204] Condensed from article contributed by J. R. Chapman, F.R.A.S.  Austwick Hall.  W. Yorkshire.  England

This star finder can easily be made by anyone who can use a few tools as the parts are all wood and the only lathe work necessary is the turned shoulder on the polar axis and this could be dressed and sandpapered true enough for the purpose.  The base is a board 5 in. wide and 9 in. long which is fitted with an ordinary wood screw in each corner for leveling.  Two side pieces cut with an angle equal to the colatitude of the place are nailed to the base and on top of them is fastened another board on which is marked the hour circle as shown.  The end of the polar axis B, that has the end turned with a shoulder, is fitted in a hole bored in the center of the hour circle.  The polar axis B is secured to the board with a wooden collar and a pin underneath.  The upper end of the polar axis is fitted with a 1/4-in. board, C, 5-1/2 in. in diameter.  A thin compass card divided into degrees is fitted on the edge of this disk for the declination circle.