THE YOUNG FARMER'S MANUAL. 429 



York city, and by Andrews & Burbage, Elmira, N. Y. Their 

 patent ground circulars sustain an unrivalled reputation through 

 out the States, not only for sawing lumber, but for farmers' wood- 

 saws. : *The patent ground circulars are thicker in the centre than 

 they are at the cutting edge, and are ground of a uniform taper 

 from the centre to the edge, which shape renders them stronger 

 than those which are ground in the usual manner ; and they 

 require less set, and, as a consequence, less power is required to 

 drive them ; and they are less liable to become heated ; and they 

 do not wear out so many files, because the teeth are thinner ; 

 and, more than all, they possess a superior temper ; and are made 

 of the best of steel. I have two of them in use, and although I 

 am a stranger to the manufacturers of these saws, I would not 

 exchange one of these saws for a gross of common saws. If a 

 farmer desires a good saw of any kind, and made of any thick 

 ness, or of any style of teeth, or if he has an old saw which needs 

 to be re-toothed, or re-tempered, or straightened, he need not fear 

 to confide in either of these companies. 



HANGING CIRCULAR SAWS. 



656. It is a pretty nice piece of work to hang a circular saw 

 just right. It is an impossibility to make a saw mathematically 

 true, or to hang it to run with mathematical precision ; but it is 

 easy for a good mechanic to approximate as near perfection in 

 this respect as is of practical use. A good saw is often con 

 demned when the whole fault is in the mandrel on which it turns ; 

 and a badly fitted mandrel is liable to spoil a good saw. 



657. The idea to be kept in mind is, to have the collars or 

 flanges turned as true as possible ; and any deviation in the col 

 lars from trueness, will multiply this deviation in the saw just as 

 many times as the saw is larger than the collars. The bearings 

 of the mandrel should be turned first, and then the face of the 

 collar should be turned off very true, without changing ends of 

 the mandrel in the lathe. Sometimes the centres or points in a 

 lathe deviate a trifle, and by changing ends with the mandrel, 

 a,nd finishing a part of it with the ends in opposite directions, the 



