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. 



