THE WORLD'S ADVANCE 



223 



ably by using short lengths of worn out 

 files. The files should be annealed and 

 cut into short lengths, and a hole drilled 

 in one end for a nail. 

 Contributed by 



CHARLES H. ANDERSON. 



Instead of Tapped Holes 



Difficulty is usually experienced in 

 tapping holes in thin metal. A simple 

 method which will accomplish the same 

 results is to bore a hole somewhat larger 

 than the shank of the screw and solder 

 a nut, tapped for the same thread as the 

 screw, on one side of the opening. 



Contributed by 



WALTER FRANSEEN. 



Useful Device for the Stove 



This is a heat-retaining cover for flat 

 irons having detachable handles. Inci- 

 dentally it can be used as a potato-baking 

 oven. The construction follows : 



Separate two deep pie pans about ten 

 inches in diameter with several layers of 

 sheet asbestos. Clamp them together 

 with a bolt passing through a hole in the 

 centre of the bottoms and terminating 

 in a wood spool. 



In use, the pans should be placed upon 

 a square board of asbestos, which in 

 turn is placed upon a ring of iron. 



Contributed by C. H. PATTERSON. 



Improvised Wood Clamp 



In constructing the table which was 

 described in the April issue of THE 

 WORLD'S ADVANCE, the writer experi- 

 enced considerable difficulty in clamp- 

 ing the ends together. However, he 

 finally hit upon the plan which is illus- 

 trated in the accompanying drawing, and 

 it accomplished the desired results very 

 satisfactorily. 



Contributed by 



E. A. HODGSON. 



A Chart for Computations 



In all computations involving a com- 

 mon factor and this applies to a great 

 many workshop and laboratory problems 

 the short cut described below will be 

 found useful. A large sheet of paper 

 should be ruled with fifty lines in one 

 direction and sixteen in the other. In 

 the first column the consecutive numbers 

 from 2 to 50 should be written. A de- 

 cision should then be made as to what 

 factors are the most commonly used. 

 One commonly used factor is 3.1416, 

 which is used in determining the differ- 

 ent values of circles. One of the re- 

 maining columns should be headed with 

 this number, and the various products 

 of 3.1416 found by multiplication and 

 inscribed in the various columns from 2 

 to 50 (or from 2 to 99, if provision has 



