Page:Popular Science Monthly Volume 91.djvu/303

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it takes only about 10 minutes for the volcanic phenomena to begin to appear.

In Nature layers of hard rock or similar obstruction may deflect the rising fumes,

���The miniature volcano in action as it ap- pears from the lake end of the box

and this may be imitated by placing a sheet of slate in the sand, as the dark line shows, a short distance from the bottom of the basin. With this plate in the sand several vol- canoes may be produced in line with its upper edge. By this arrangement the vol- canic action will appear at some distance from the source of heat. This illustrates how linear groups of volcanoes are formed in Nature. By varying the positions and the number of plates the volcanic action may be concentrated near the top.

��Popular Science Monthly 287

A Double-Deck Revolving Clothes Hanger for a Yard

WHERE backyard space was at a premium, the double-deck clothes- line apparatus, shown in the illustration, was made to serve the purpose of drying as satisfactorily as the ordinary line that takes up so much room. The double-deck ar- rangement is built on a center upright made of 25 ft. of 2-in. galvanized pipe purchased from a local plumber. The arms consist of 10 sections of i-in. pipe about 6 ft. long, threaded on both ends to fit into caps and bands that slip over the center pipe. The bands are movable, being held in place by a shoulder. Wires are strung around from end to end of each extension and each arm is supported by a wire. Two of these are placed on the center post, one for the ground level and the other for the second floor porch. The height for each hanger is adjustable. The lower hanger can be made just as high as it is desired by the person using it. The top circle can be arranged to reach the rear window or porch. The main pole is embedded in 3 ft. of concrete, affording a rigid foundation. The apparatus covers a circular space of the back yard about 12 ft.

��A Solution for Reclaiming Over- Exposed Blue Prints

WHEN washing blue prints, if 10 drops of peroxide are added to each gallon of water a solution will be made that will produce even blue prints. The blue print is washed as usual in clear running water, after which it is placed in the peroxide solution and is finally washed m clear water to remove all traces of the salt. A blueprint of correct exposure or one under exposed will not be affected by it, but in over ex- posure the chemical will restore it to the true color. Where old blue prints have be- come faded this solution will restore them.

���Two sets of clothes hangers on a single pole serving a two- apartment house

in diameter and has more than 150 ft. of hanging space. — Charles M. Stewart.

�� �