THE WHEAT CTJLTUillST. 



331 



and compact rake, the working parts being all of iron, 

 and put together in a very substantial manner. 



Keeping Knives Shaep. 



As the cutters of mowers and reapers sever the stems 

 of grain and grass with a crushing stroke, it is of the 

 utmost importance that the cutting edge should be 

 sharp. Besides this, the angles which the cutting sides 

 make with the base must be accurately adjusted to the 

 rapidity of their vibrations, and their temper must be 

 such as to insure the best cutting edge. Experience 

 has shown that, where the whole section is tempered, 

 it is too frangible for practical use. The slightest con- 

 tact with stones, sticks, or other obstructions, causes it 

 to fly in pieces like glass. The central portion of the 

 section should therefore be left soft, while the temper- 

 ing is confined to a portion extending from one-half to 

 five-eighths of an inch from the edge. The violent 

 change in the structure of the metal, lying on either 

 side of the line of demarcation (see Fig. 53), often causes 

 a fracture, resulting in loss to the manufacturer or the 

 farmer, according to the time when the fracture appeared. 



The illustration on the next page represents a knife, 

 or section, manufactm-ed by Reynolds, Barber & Co., 

 Auburn, I^ew York. The committee appointed by the 

 'New York State Agricultural Society to examine these 

 sections, state that " all of the Messrs. Reynolds' sec- 

 tions conformed to their test through ten successive 

 grindings. Several of the others broke when pressed 

 upward at an angle of fifteen degrees. Some of them 

 bent permanently, when pressed upon, l^one of them 

 except Messrs. Reynolds' showed a good temper after 



