Popular Science Monthly
��position so as to drain into a sink, wash- basin, bath-tub, laundry-tray or barrel. The hose is connected with a cold water faucet, the trough almost filled and the inlet and outlet regulated to maintain a constant depth of water in the trough. The film, with a film clip attached to each end, is laid in the running water, emulsion side up, or, better still, stood on edge where possible. Film pack negatives may be pinned on a stick the exact length of the trough and placed in the running water.
��Safety Guard Placed on an Emery-Wheel Dresser
IN the crusade for "safety first" attach- ments on machine tools, one that is likely to be overlooked is the emery-wheel dresser. This, however, has been taken care of in a very efficient manner in one shop as illustrated. A piece of 1/16-in. boiler plate about 2 in. wider than the
���Metal guard attached to the handle to prevent flying particles from striking the eye
cutting wheels of the dresser was bent and fastened with two 3/16-in. screws about % in. long on the handle of the dresser for a guard. — Joseph K. Long.
��A Nest- Box Trap for Catching the English Sparrow
SPARROW traps may be classified, according to the U. S. Department of Agriculture, as nest-traps and bait-traps. Inasmuch as sparrows usually feed in flocks, but approach nest-boxes singly or in pairs, the annual catch of a bait-trap will exceed that of a nest-box trap many times; but during the breeding season the nest-box traps are decidedly useful.
A nest-box trap, as the name implies, looks like an ordinary nest-box. The weight of a bird entering such a trap puts into operation a mechanism which catches the bird and sets the trap for another. There are a number of devices to accomplish this. In designing a nest-box trap one
��should bear in mind that English sparrows, like other birds, dislike drafty quarters, and that a mechanism delicate enough to be operated by a sparrow's weight is likely to get out of order unless the parts are few
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� ��A trap-nest for catching the English spar- row in a bag hung from beneath the box
and perfectly protected from the weather.
Probably the simplest nest-box trap yet designed is the one illustrated. The essen- tial parts of the trap are: a box, a tipping chamber within the box, a down-spout below it and a bag at the lower end of the down-spout. The dimensions of the several parts are given in the illustration. The tipping chamber is made of tin, the down- spout of wood or tin, the box of wood. The roof board is cleated across the ends, and also lengthwise between the cross cleats, for the attachment of the sides, as shown in the side elevation.
The close weave of a 2-bushel bag makes it suitable for the lower end of the down- spout. One of coarser fabric would allow a draft through the spout and thus detract from the efficiency of the trap. In building this trap the front wall is the last piece to put in place. It is fastened there with screws so that the trap can be easily over- hauled. It is a good plan to fasten with shellac a few feathers or bits of hay to the floor of the tipping chamber near the rear end to excite the interest of the sparrows.
��Look Over Stored Tires Before Applying Them to Rims
BEFORE using tires laid aside examine them carefully for cuts on the outside, remove tacks and small nails, reinforce any breaks in the fabric inside and lubricate the fabric and inner tube with powdered mica. Apply a thin solution of graphite, shellac and alcohol according to instructions.