Do It with Tools and Machinery 



A hammer with 

 removable faces 

 of any desired 

 size or shape, 

 of steel, copper 

 or other soft 

 metal to suit 

 different work 



A tackle for unloading automobiles. The ropes 

 are adjusted so as to lift vertically on each of 

 the four wheels. The main member is a scantling 

 suspended lengthwise of the automobile 



The same ham- 

 mer at left 

 with a steel face 

 for ordinary 

 work requiring 

 heavy pounding. 

 Other faces may 

 be substituted 



A boiler ther- 

 mostat for indi- 

 cating heat in 

 chemical vat3. A 

 rod extending 

 the length of 

 the outer shell 

 supports the 

 bimetallic strip 



Above: A new valve 

 grinder designed 

 for engines equip- 

 ped with valve caps 



In center: A new machine used in post- 

 effices for tying envelopes into packages. 



A quick-action 

 chuck with 

 which a rotative 

 tool can be re- 

 moved and an- 

 other inserted 

 while the ma- 

 chine spindle 

 is revolving 





Above: A nut lock 

 which prevents a 

 nut from backing 

 off from a bolt 



It ties from twenty-five to thirty 

 bundles a minute with a non-slip knot 



399 



