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six pounds. His chissels are a little 
broader than the file, sharpened to an angle of about 
20 degrees. The length is sufficient to be held fast be- 
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Seng upon prop on the other of the strap. When 
of is single fine file 
Sanne the seit to pag hina. '90§ 
325 
bastard cut fineness, a quick workman will make about 
800 strokes, and as many teeth in one minute. 
The smaller files are generally cut by women and 
children, who very soon acquire great dexterity. 
' The file-cutter, whatever ma the degree of fine- 
ness of the file, depends phe 
File. 
more upon his feel- 
“ing than his eyes. Indeed, their ors are frequently 
directed to other objects while the and the ham- 
mer are going at the full rate. 
When one tvoth is formed, the edge of the chissel and 
the surface of the file being both very smooth, the for- 
mer is pushed up against the back of the first tooth, 
which can be much felt than seen. By this suc- 
cession of stroke and motion of the chissel, to feel the 
last tooth, the work is performed, although the eye is 
at a considerable distance from the work. 
When the files are cut, the next process is to harden Process of 
them, This is effected by heating them to redness, hardening 
and quenching them in cold water. Some previous 
steps are taken to prevent the action of the oxygen of the 
atmosphere upon the file when red hot, anda peculiar 
manner of immersing the file in the water, which we 
shall more particularly dwell upon. 
The preparing process has beenimproved within these 
ten years, so far as economy. The files were, 
before that time, first smeared with the residuum of ale 
barrels, commonly called ale grounds, and then covered 
over with common salt in powder, which was retained 
merely by the adhesive nature of the ale grounds. They 
were now dried before the fire. The files were now 
taken once or twice and heated in a smith’s fire, made 
of small coaks, frequently moving the file backward 
and forward, in order to heat it uniformly red hot. At 
this period the file gives off a white vapour from the 
surface, which is the salt in the act of subliming. The 
surface a at the same time covered with the salt 
ina liquid state, which, like a varnish, preserves the 
surface from the oxygen of the atmosphere, during the 
time it is red hot. ‘The file is now held in a perpendi- 
cular position, and the immersion in the water com- 
mences at the point, slowly di ing it up to the 
tang, which shoald not be hardened: An files are dip- 
ped in a perpendicular direction. Those, however, which 
ve a round side and a flat one, are nioved also in a 
horizontal direction, with the round side foremost. With. 
out this precaution, files of this shape would warp to- 
wards the round side. This arises from the flat side 
having been more hammered than the round side, which 
is formed by the concave die, and does not acquire the 
same density which the hammer gives. 
It is common after hardening to temper most cut- 
ting instruments. Files, however, are never tem 
at all by the maker. Nor are any but rough and the 
bastard-cut files tempered by those who use them. If 
these were not in. some cases tempered, the points of 
the teeth would break, and the file would do but little 
service, 
When files are hardened, they are brushed with wa. 
ter and coak-dust. The surface becomes of a whitish- 
grey colour, as perfectly free from oxidation as before 
it was heated. 
In ing the salt as above directed, a very great 
of it is rubbed off into the fire and is lost. 
consumption of salt used in this manufacture at 
Sheffield alone, amounted to about £1000 annually. 
The economy with which it is now used, has reduced 
this quantity to less than £300. This saving is ‘effect- 
ed by mixing ale grounds and the salt together, the 
