THE YOUNG SCIENTIST. 
141 
stone and remaining there while the tool is 
being sharpened, will often seriously injure 
a fine tool, and great care is therefore re- 
quired in this respect. To keep an oil- 
stone in good condition, it must be kept 
clean and free from old gummed-up oil. 
When the oil becomes thick and gummy, 
the tool slides over it without being ground 
away, and your labor is lost. The best kind 
of oil, in our opinion, is good sweet oil. 
Some recommend kerosene, but we have 
found that it hardens the stone and injures 
it. It is also necessary that the stone for 
sharpening chisels, etc. , should be kept per- 
fectly flat. "When it becomes irregular, the 
best method of making it true is to grind it 
down upon some flat gritty stone, with 
water, and afterwards smooth it off by rub- 
bing it over with a flat slate charged with 
very fine emery. After having cleansed off 
the stone carefully, put a little oil on it, 
take one of your chisels, the handle in your 
right hand, put it on the stone, and holding 
it at the angle at which it has been ground, 
place the fingers of the left hand on the 
face, and with a moderate pressure rub it 
steadily backwards and forwards, looking at 
it frequently to see if you do not get it 
down too much, and make what is called a 
wire edge. When it is sharp enough, raise 
your right hand a little, give the edge of 
the chisel a semi-circular forward sweep or 
two on the stone; then turn the face down, 
give it two rubs with a semi-circular forward 
sweep, and your chisel will be sharp. If you 
should get a wire edge, draw the tool over 
the edge of a table or board, and it will 
come off. If this does not remove it, stick 
the tool upright on the table, and bend it 
backwards and forwards; then put it on the 
stone again, giving it, with the hand raised, 
the semi-circular sweep we have before de- 
scribed. Sharpen your gouges in the same 
way, only you must keep turning your 
hand as you rub to and fro, so that each 
part of the edge of the gouge may come in 
contact with the stone. We sharpen our 
gouges in a manner different from most 
people. We hold the gouge across the 
stone, giving it a rocking motion by turns 
of the wrist, as we push it up and down the 
stone. To explain: Bring the gouge close 
to you, holding it across your body; put the 
further comer of the gouge down on the 
stone, push from you, and at the same time 
turn your wrist, so that the upper or near- 
est corner comes down on the stone; draw- 
ing it back, reverse the motion, and in this 
way every part of the edge of the gouge 
will be equally ground by the stone. We 
have found this by far the best plan, as the 
edge does not get rubbed away more in one 
place than in another. Then , as you can 
not sharpen the face, which is hollow, on 
the oil stone, take the sli^.) between the 
finger and thumb of your eight hand, and 
holding: the gouge firmly inthe left, sharpen 
the inside of the tool. Take care not to rub 
away too much of the face of your tools, 
for it is the hardest and most precious part. 
The V tool is the most difficult of all to 
sharpen. This must be done with the flat 
side of the slip, and take care that it is not 
more rubbed on one side than the other. 
It will requ re considerable practice and 
much patience to learn to sharpen this tool 
well; but in this, as in all other things, re- 
member the old Spanish proverb: "With 
patience and perseverance the mulberry leaf 
becomes a silk gown." The final touches, 
which give to the tools the last degree of 
sharpness and smoothness of edge, are 
given on a piece of stout leather, about an 
inch and a half wide and eight inches long, 
glued to a board, and rubbed over with the 
very finest emery paste, which is emery 
made into a stiff paste with tallow. The 
emery must be perfectly free from grit; and, 
to obtain it in this condition, you must get 
some of the very finest flour of emery and 
mix it with water in a tall jar, such as a 
good-sized fruit jar. After stirring it up 
vigorously, allow it to settle for say a min- 
ute; pour off the liquid into another vessel, 
and allow the fine powder that remains in 
it to settle completely. Pour off the liquid, 
dry the powder, and keep it for use. The 
strop should be kept carefully covered, to 
protect it from dust; and, if the emery be 
good, it will impart to your tools an edge 
