Page:Popular Science Monthly Volume 89.djvu/217

 Popular Science Movthhf

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��can be done at four ihoiisaiid feet, in which case the width of the field is al)out two thousand, four hunchx'd leel.

Suppose a scout is given orders to photograph the entire territory occupied by the enemy. He reguhites his camera, soars aloft, and when over the enemy's trenches at an altitude of two thousand feet, for instance, turns a lever which releases a propeller in front of a gear box, which, in turn, starts the camera mechan- ism in motion. Instantly he obtains a continuous photograph of the earth's surface one thousand, two hundred feet wide.

Should he desire to get more useful infoniialion by continuing his flight at a higher altitude, he stops the camera mechanism and ascends to twice the height. There he makes a readjustment of the apparatus and continues his flight, taking a continuous photograph meantime. Mile after mile he continues, until, if he so wishes, he can obtain a photographic record of one himdred and thirty miles of the enemy's territory.

Briefly, the camera consists of a camera bo.x cc)ntaining two rollers round which the film is carried. The film has a scries of perforations along one edge, and a toothed stop is provided to engage with these and hold the film motionless when required. The box is impervious to light, and has a lens pointing down- ward, through which the main photo- graph is taken. It has also another lens pointing directly upward, which pro- duces photographs at desired inter\-als of the exact position of the compass and aneroid needles situated in the holding case above. This last-named photograph automatically registers on the film the direction and altitude of the aeroplane when the exposure was made.

The film rollers arc driven by a propeller through the gear box. The hand le\er controls the intervals of ex- posure by varying the speed of the shaft as compared with that of the propeller. The shaft may be operated by hand through the lexer and a single photograph he taken, the i)ro|)eller lieing for the moment put out of gear.

���The ingenious baseball sewing-machine which pulls the covers together and stitches them

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��A Machine That Stitches Baseball Covers

SEWING-MACHINE has been in- •ented for stitching together the co\ers of a baseball. It has a mechan- ism for holding the ball in position while it is being stitched and pulls the covers together over the ball while the stitch is being taken.

The clamping jaws hold the ball while a wheel abo\e is turned to bring its needle gripping fingers into position to outwardly grip and release the needle which sews the covers. A cam device regulates the needle action.

���This can will trap every inquisitive animal that sticks its head into it

��Trapping Animals by "Canning" Them

AFI\T£-gallon gasoline can . cut at the top from corner to corner and with the sharp edges bent inward, constitutes a trap foranimals that never fails to work. When the animal enters the can with its heat! the sharp edges pre\'ent it from ex- tracting it and escaping.

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