If it is desired to make the light very complete, make the base of two pieces of brass tube—­one being a sliding fit in the other and with projecting pieces to prevent the cylinder from going too far.  The light may then be elevated or lowered as wished.  On two ordinary brass terminals twist or solder some flexible wire, but before doing so fix a little bone washer on the screws of the terminal so as to insulate it from the tube.  When the wires have been secured to the terminals cover the joint with a piece of very thin india rubber tubing, such as is used for cycle valves.  The two wires may now be threaded down the copper tube into the base, and pulled tight, the terminals firmly fixed into the tubes; if too small, some glue will secure them.  To get the cylinder into its carriage, put one trunnion into the terminal as far as it will go and this will allow room for the other trunnion to go in its terminal.

** Electric Alarm that Rings a Bell and Turns on a Light [337]

The illustration shows an alarm clock connected up to ring an electric bell, and at the same time turn on an electric light to show the time.  The parts indicated are as follows:  A, key of alarm clock; B, contact post, 4 in. long; C, shelf, 5-1/4 by 10 in.; D, bracket; E, electric bulb (3-1/2 volts) ; S, brass strip, 4-1/2 in. long, 3/8 in. wide and 1/16 in. thick; T, switch; F, wire from batteries to switch; G, wire from bell to switch; H, wire from light to switch; I, dry batteries; J, bell; X, point where a splice is made from the light to wire leading to batteries from brass strip under clock.  Push the switch lever to the right before retiring.

To operate this, set alarm key as shown in diagram, after two turns have been made on the key.  When alarm goes off, it turns till it forms a connection by striking the contact post and starts the electric bell ringing.  Throw lever off from the right to center, which stops bell ringing.  To throw on light throw levers to the left.  The bell is then cut out but the light remains on till lever is again thrown in the center,

[Illustration:  Details of Alarm Construction]

In placing clock on shelf, after setting alarm, be sure that the legs of clock are on the brass strip and that the alarm key is in position so it will come in contact with the contact post in back of clock.  The contact post may be of 1/4-in. copper tubing, or 1/4-in. brass rod.

The advantage of this is that one can control the bell and light, while lying in bed, by having the switch on the baseboard, near the bed, so it can be reached without getting out of bed.  —­Contributed by Geo. C. Brinkerhoff, Swissvale, Pa.

** How to Hold a Screw on a Screwdriver [337]

A screw that is taken from a place almost inaccessible with the fingers requires considerable patience to return it with an ordinary screwdriver unless some holding-on device is used.  I have found that by putting a piece of cardboard or thick paper with the blade of the screwdriver in the screw head slot, the screw may be held and turned into places that it would be impossible with the screwdriver alone.  —­Contributed by C. Chatland, Ogden, Utah.