762 



Popular Science Monthly 



cannot be made immune. Watches are 

 being constructed now witii non-magnet- 

 ic alloys in place of steel; but the alloys 

 are not perfectly satisfactory. 



The effects of temperature are taken 

 care of more easily. The impairment of 

 the hair-spring function is compensated 

 for by the construction of the balance 

 wheel, which has a rim of fused brass 

 and steel. Each metal re-acting in 

 differing degree to temperature, the 

 variance in its contraction or expan- 

 sion under the influence of cold or hear 

 produces a bending of the rim, formed 

 by two half-circle arcs. These are 

 arranged and constructed so that the 

 variation in the balance wheel will 

 compensate for the variation in the 

 hair-spring. 



Many have wondered what is the 

 purpose of the little screws on the 

 edge of the balance-wheel rim. The\- 

 are to give the wheel the exact weight, 

 by their adjusted arrangement, to make 

 the proper number of revolutions and to 

 make even more accurate the balance 

 wheel's compensation for \'ariation in 

 the action of the hair-spring under 

 temperature effects. When heat weak- 

 ens the spring, it reduces the diameter 

 of the balance wheel to correspond 

 exactly for compensation. 



A Combination Tool With 

 Many Uses 



A VERY hand) tool can be made from 

 tool steel 14 in. long, 3 in. wide and 

 ^ in. thick. The teeth in the purl ,1 can 

 be made with a three-cornered or hall 

 round file. A hole is drilled near the 

 edge and the metal filed to shape as 

 shown at B to make a bottle-opener. 

 The hole C is used as a universal nut- 



A combination bottle-opener, nut-wrench, 

 saw-set, screw-driver and tack-puller 



wrench. Two slits are cut in the edge 

 at J) to make a saw-set. The end E 

 is tiled to make a tack-pulKr. 



Marking Points to Bore Holes 

 for Dowels 



D( )WEL joints must be exact. A 

 good method for marking simul- 

 taneousK' in both pieces is shown in the 

 drawing. A piece of tin or thin sheet 

 metal is cut to convenient size and a bit 

 of wire inserted in the exact center and 



Marker to locate points for boring holes sim- 

 ultaneously in dowels to make neat joints 



soldered, so that a part of it will 

 project on each side of the sheet. To 

 locate the center of the metal, draw cross 

 lines diagonalh' from the corners. The 

 point where the lines cross will be the 

 exact center. 



A more elaborate marker, large enough 

 for all work, can be made from sheet 

 brass or copper, with lines drawn parallel 

 to each other, beginning at each side, }^ 

 or 3^^ inch apart. These lines should be 

 numbered, starling with l from the out- 

 side edge and finishing near the center. 

 When placed on the end of a square or 

 rectangular piece the center can be 

 located with these lines and numbers. 



Place the marker on the end of the 

 piece; then set it in the exact place on 

 the other piece of wood and strike it. 

 The pin points will mark both pieces. 



Painting a Ladderless 

 Standpipe 



PAINTING a ladderless st.mdpipe 

 pr()\ed to be too great a prohiiin 

 for sewral contractors, but it was solved 

 by an old painter. He found out how 

 long it would take to fill the pipe, and 

 I hen had it emptied. He took se\eral 

 huge timbers insitle and built a raft, 

 after which he ordered the doors closed 

 and the pipe tilled. H\- the time the 

 inflowing water had borne his mil to 

 the top, he had accomplished his pur- 

 pose. HaKOI.D HoKlNK. 



