294 



Popular Science Monthly 



A 



A 



A Home-Made Football Inflater 



V A L V E 

 from an old 

 bicycle tire or an 

 inner tube is a 

 very serviceable 

 substitute for the 

 expensive and 

 delicate pumps 

 used to inflate 

 footballs. Cut the 

 metal ring and 

 the rubbed pad 

 from around the valve, and the inflater 

 is ready for use. 



Insert it into the neck of the foot- 

 ball, attach the outer end of the valve 

 to a bicycle pump, and your football may 

 be quickly inflated. 



A Dust-Proof Bottle for Acid 



GLASS 

 spirit lamp 

 makes an excel- 

 1 e n t bottle for 

 keeping small 

 quantities of ni- 

 tric acid, solder- 

 i n g spirit or 

 other acid liquids. 

 A glass rod may 

 be left in the 

 lamp and covered with the ground cap 

 as shown in the illustration. The cap 

 usually makes a very good fit, and for 

 many purposes no other stopper is re- 

 quired. 



When used to contain nitric acid, for 

 testing gold, however, the other device 

 shown may be adopted. A piece of glass 

 rod is drawn out to a rather fine point 

 at one end and passed through a per- 

 forated India rubber cork, which forms 

 an air-tight stopper. 



A Multiple Punch 



PUNCH 

 for making 

 a number of 

 holes in sheet 

 fibre or metal can 

 be made from a block of steel machined 

 as shown in the accompanying drawing. 

 A punch of this type is intended for 

 work that must be repeated with uni- 

 form results. 



An Oil Tray Made Without Solder 



OIL trays which 

 require n o 

 soldering may be 

 made from a 

 piece of tin of 

 such thickness 

 that it may be 

 readily bent. The 

 tin should be 

 marked off as in 



the illustration. Bend the sides up 

 on the Hues AB and CD; then bend 

 them back to their former place. Do the 

 same with the ends on the lines XY and 

 MN. Take the corner BY and bend 

 along the line RT until the side and 

 end come together and form a square 

 corner, as in lower drawing. Bend the 

 projection up against either the end or 

 side. Do likewise to the remaining 

 corners. 



Parcel-Carrying Rack for Bicycle 



THE accom- 

 panying line 

 drawings show 

 a simple pack- 

 age-carrying at- 

 tachment for a 

 bicycle, which 

 can be cheaply 

 and easily made and removed or at- 

 tached simply. The drawings show 

 clearly the method of bending and the 

 dimensions. Make the pocket to suit the 

 handle bar of the bicycle. 



Switch Detects Bad Ignition 



IT is often a te- 

 d i o u s and 

 troublesome mat- 

 ter to determine 

 which cylinder of 

 a multiplex cylin- 

 der engine is 

 missing explo- 

 sions. A very sim- 

 ple little instru- 

 ment, shown in 

 the accompanying 

 sketch, renders the discovery of the 

 missing cylinder easy. It is simply a 

 switch, to be fastened to the spark plugs 

 in succession. 



