[Illustration:  Automatic Time Draft-Opener]

falls away, releasing the weight, which pulls the draft open.  —­Contributed by Edward Whitney, 18 Gorham St., Madison, Wis.

** How to Transmit Phonograph Music to a Distance [107]

An interesting experiment, and one calculated to mystify anyone not in the secret, is to transmit the music or speech from a phonograph to another part of the house or even a greater distance.  For an outdoor summer party the music can be made to come from a bush, or tree, or from a bed of flowers.  The apparatus is not difficult to construct.

The cut shows the arrangement.  Procure a long-distance telephone transmitter, D, including the mouthpiece, and fasten it to the reproducer of the phonograph.  Also a watch case

[Illustration:  The Long-Distance Phonograph]

receiver, R, which fasten to the horn.  These parts may be purchased from any electrical-supply house.  Connect two wires to the transmitter, running one direct to the receiver, and the other to the battery, thence to a switch, S, and then to the receiver.  The more batteries used the louder will be the sound produced by the horn, but avoid using too much battery or the receiver is apt to heat.  —­Contributed by Wm. J. Farley, Jr., Camden, N. J.

** How to Make a Telescope [108]

With a telescope like the one here described, made with his own hands, a farmer boy not many years ago discovered a comet which had escaped the watchful eyes of many astronomers.

First, get two pieces of plate glass, 6 in. square and 1 in. thick, and break the corners off to make them round, grinding the rough edges on a grindstone.  Use a barrel to work on, and

[Illustration:  Homemade Telescope]

fasten one glass on the top of it in the center by driving three small nails at the sides to hold it in place.  Fasten, with pitch, a round 4-in. block of wood in the center on one side of the other glass to serve as a handle.

Use wet grain emery for coarse grinding.  Take a pinch and spread it evenly on the glass which is on the barrel, then take the glass with the handle and move it back and forth across the lower glass, while walking around the barrel; also rotate the glass, which is necessary to make it grind evenly.  The upper glass or speculum always becomes concave, and the under glass or tool convex.

Work with straight strokes 5 or 6 in. in length; after working 5 hours hold the speculum in the sunshine and throw the rays of the sun onto a paper; where the rays come to a point gives the focal length.  If the glass is not ground enough to bring the rays to a point within 5 ft., the coarse grinding must be continued, unless a longer focal length is wanted.