This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
By CLAUDE L. WOOLLEY
The following apparatus is likely to be novel, and certainly very striking when erected on country estates, particularly on high lands, hillsides, and along the seashore, where the flashes may be seen for many miles out at sea.
It is not unusual in country gardens to see a large hollow glass globe silvered on the inside, mounted on a pedestal, brilliantly reflecting the sunlight. The apparatus described is an elaboration of the idea. The drawing shows in diagram the general construction, exact measurements not being given. However, a convenient height is 3 1/2 to 4 ft., and the circular frame, carrying the mirrors, may be 10 to 14 in. in diameter.
The supporting frame, of galvanized sheet iron or sheet copper, may be either circular or hexagonal in shape. Mounted upon a vertical shaft is a skeleton circular frame, carrying a double row of small mirrors, or ordinary flat mirror glass, mounted in grooves provided for them ; the upper row inclined slightly upward, and the lower row slightly downward. If a greater number of angles of reflection are desired, the mirrors may be smaller, and arranged in four circular rows instead of two, each row being inclined at a slightly different angle.
The shaft is pointed at the lower end and rests in a bearing drilled with a V-shaped depression, the bearing being supported by soldering or riveting at each end to the inner sides of the pedestal shell. The upper portion of the shaft passes through a bearing which is also soldered or riveted at the ends, to the inner surfaces of the pedestal shell.
The mirrors, mounted on the shaft, thus are free to revolve vertically with very little friction. Upon the lower end of the shaft is fastened a light gear wheel of rather large diameter, and this in turn is geared to a smaller gear mounted on the end of the armature shaft of a small electric motor of the type that may be driven with a few dry cells; the relation of the sizes of the gears being such as will cause the mirrors to revolve slowly, when the motor is running at normal speed.
Ill: The Flasher as It Appears on the Stand and the Details of Its Construction
Connected to the motor are two or more dry, or other suitable batteries, a small door being provided on the side of the lower part of the pedestal to enable the batteries to be replaced, or turned off, and to give access to the motor. A circular shield is erected over the mirror carrier, surmounted by an ornamental ball, to protect from the weather and to provide a more finished appearance. A waterproof canvas cover may be slipped over the whole in rainy weather.
As new mirror faces at varying angles are constantly being presented to the sun, vivid flashes are constantly occurring when viewed from almost any angle or position on the side where the sun is shining. The circular shield on top is supported in position by four metal strips secured by soldering to the shield and the supporting pedestal.
Such a device may be constructed without much expense, producing a most brilliant effect over miles of territory. The small driving motor may be replaced with a suitable spring or weight-driven clockwork; or four hollow hemispherical metal cups may be mounted on arms, or placed at right angles, and the arms in turn mounted upon a vertical shaft and arranged above the mirror carrier and geared in such manner that the mirrors will revolve slowly, while the cups are revolving with comparatively high speed by the force of the wind.
The mounted revolving cups are similar in form to the apparatus used by the U. S. Weather Bureau for measuring the speed of the wind. They will respond to a good breeze from any point of the compass.