4 
THE YOUNG SCIENTIST. 
the operation of cutting ; this makes the 
work wavy and full of transverse ridges, 
thus rendering the work unsatisfactory. 
Notwithstanding these defects, it has 
been ascertained that an angle of 25° is 
the proper one to employ when grinding 
tools for wood-working. To guard against 
the defects mentioned, a second basil is 
made at the cutting-edge at an angle of 
35°, as shown at a, Fig. 4. It will be seen 
Fig. 4. 
that by this method all the defects of the 
thin cutting edge are avoided, and all its 
advantages maintained. In grinding, 
care should be taken to avoid finishing- 
down to the edge, for if such is the case 
the edge would be ragged and broken 
up, and would have to be whetted 
down on the oil-stone a full 32nd of 
an inch before the cutter would be 
ready for use. 
In grinding tools of this character, 
the stone should revolve from the 
operator ; that is, the top of the stone 
should move away from, not towards 
the tool. This gives the operator bet- 
ter control of the work, and gives 
him an opportunity to see when to 
cease grinding, which should occur 
when the basil is brought to within 
about a 32nd of an inch of the edge. 
The process of sharpening should be 
completed on the oil-stone at an angle of 
35°, as shown at Fig. 4. 
This second basil need be no more than 
a 16th of an inch from the cutting-edge 
to its termination on the line of basil; 
a 32nd of an inch is quite enough for the 
first few whettings after the tool is ground. 
Another thing I warned my friend 
against, and that was making a rocking 
motion of the hand while whetting the 
cutter, as this motion has a tendency to 
give the basil a convex or rounding shape, 
something like that shown at Fig. 1, 
which after a while destroys the cut- 
ting qualities of the edge. During the 
sharpening process on the oil-stone, the 
tool should be held firmly in the hand, 
with the thumb on one edge and two fore- 
fingers on the upper side of th-e iron, as 
shown at Fig. 5, with the end resting 
against the ball of the hand. The tool 
should now be placed on the stone and 
the left hand brought over and pressed- 
on it as shown at Fig. 6. Sometimes the 
operator will find it more convenient to 
rest the three forefingers of the left hand 
on the iron while sharpening; on the 
whole, however, I prefer running the 
Fig. 6. 
hand over, as shown in the illustration,, 
as it enables one to take a very firm hold 
of the tool. With chisels, gouges, and 
other handled tools, it is better to lay on 
the fingers of the left hand than to grip 
it with the fingers, as it is not abso- 
lutely necessary that the cutting edges of 
these tools should be in a right line, or 
strictly at right-angles with the edges of 
the iron. With plane irons this is dif- 
ferent ; the cutting edge must be a right 
or straight line, and at right angles with 
the edges of the iron on the smoothing- 
plane, fore-plane, and long-jointer, but it 
