THE YOUNG SCIENTIST. 
95 
resembling the run of a screw will appear ; 
but by practice it will show itself, and 
must be then followed on to the part of 
the work where it is required. In case of 
a mishap, always leave the material both 
longer and larger in diameter than it will 
be wanted when finished, as the lead of a 
screw can generally be carried any length 
that may be required. Having practiced 
the chasing of an outside or male thread, 
we must turn our attention to the inside 
or female screw ; the principle for this is 
just the same as in the former, the front 
of the wood must be rounded off, and the 
screw tool passed in and out, with a slight 
movement of the right hand, which must 
be worked from right to left, until the 
lead is obtained. In making a box make 
the lid first, and to do this, the piece of 
wood of which the whole thing is to be 
manufactured from should be carefully 
turned by aid of the prong chuck, to fit 
into one of the metal cup chucks, the size 
of course, being chosen to suit the ma- 
terial. The fitting should be slightly 
taper, and it can then be driven tightly in. 
Practically, the wood must not bottom- 
that is, a space between it and the end of 
the chuck is always left. It is as well to 
drive the wood into the chuck by placing it 
on a solid bench, and not to commence hit- 
ting it when on the mandril, although if 
not true, it may be corrected when in its 
place. The material now being properly 
held, the first step will be to determine 
the depth of the lid, and set the turner's 
square to it ; then turn it out, taking care 
to have the inner surface perfectly flat; 
this done, take what is termed a hook 
tool, that is, a small tool turned at the 
end to a right angle, and rounded at the | 
end. Insert this in the end, where the ■ 
screw is to terminate, for the purpose of ! 
allowing the chaser to finish the screw 
without forming a ridge, or an uneven- 
ness, which will prevent the male screw 
going home to its place ; having gone so 
far, the lid must be parted from the bot- 
tom, and it will be seen at a glance that I 
the remaining portion, forming the bot- 
tom of the box, will act as a chuck upon 
which to finish the lid. The inside of the 
low^er part can now be turned to its de- \ 
sired dimensions, and the outside screwed 
to fit the top ; when this is done, the whole 
of the box can be turned off in one cut, and 
if the screws are properly fitted, it ought 
i to be difficult to find the place where the 
two parts join. The outer shape may be 
ornamented by the application of a 
smaller chisel, and very pretty plain 
mouldings accomplished. I need scarcely 
mention that where large quantities of 
any special things of one particular shape 
are required, that a moulding-tool is 
made to the shape, and this, by being 
simply inserted, forms at once the shape, 
and insures their cut being exactly alilte. 
I will now proceed a step further, and 
suggest that the next piece of work at- 
tempted should be what, for want of a 
better title, we will call a puzzle-box. 
This may sound somewhat infra dig., but 
it will bear out its name in two senses : 
first, it will be a more difficult thing than 
might be imagined ; secondly, if properly 
made, it will certainly puzzle anyone to 
extract its contents without being told 
how to do it. This box, in the first in- 
stance, shall take the shape of a ball — 
about the dimensions of a full-size bil- 
liard-ball will suffice. This, in itself, is 
no easy matter to accomplish, and it must 
be chucked several times in order to 
obtain a sphere; and if an opportunity 
should arise, I would ask anyone about 
to turn such an article to watch a billiard- 
ball turner for a little while, for although 
I am endeavoring to give all the informa- 
tion I can upon this subject, I candidly 
confess that a few hours' practical tuition 
is worth any amount of literature upon 
the same topic. We will presume, how- 
ever, that the ball is completed. It must 
be chucked firmly, and a hole, slightly 
taper, turned right through it, about 1 in. 
diameter at the smallest end, and about 
l-16th in. larger at the mouth. There is 
no rule for the sizes, and it matters little 
what they are. Having turned this per- 
fectly straight [and smooth, put it on one 
side, and turn a piece to fit it exactly. 
When this is done, the second part must 
be formed into a box, after the manner 
previously described. When this is so 
far finished, the box part is fitted into its 
place, and must be all turned off to the 
sphere as if it consisted of one piece only. 
