THE YOUNG SCIENTIST. 
45 
would rather have an old Sioux one, made 
of hickory or ash, but the boss bow I ever 
owned was made of buffalo ribs. An In- 
dian carries his quiver of arrows over his 
right shoulder, so that he can get his ar- 
rows quickly. When he has discharged 
one arrow, with the same motion that 
he uses in pulling the string he clutches 
another arrow. If he shoots one hundred 
yards he has three or four arrows in the 
air all going at the same time. It's great 
fun shooting at a bird with a long tail that 
flies over the prairie. Knock out his tail 
and his steering apparatus is gone. I 
have knocked the tail out of many a one, 
and so caught him in my hands when he 
* tumbled."— i^oresi and Stream. 
Cheap Lathes and How to Use Them. 
III. 
HOW TO CHOOSE A LATHE. 
HAVING decided as to the size and 
general character of the lathe that 
will best suit our requirements, the next 
thing to be done is to select from those in 
market a well-made sample of the kind of 
lathe that is wanted. 
If the lathe be a very cheap one, it must 
not be expected to be perfect in its parts 
and movements. Still, even in this case, 
the spindle should run easily, the balance 
wheel should have sufficient weight, and 
the framework should be firm and with- 
out shake. To test the movement of the 
lathe, whether it be cheap or dear, throw 
off the band and turn the spindle by hand. 
It should move very easily and yet with- 
out shake, and when tightened a little in 
its bearings, so that it runs just a trifle 
stiffly, it should move quite as easily at 
one part of its revolution as at another. 
The latter is a principal point to be at- 
tended to in all lathes. If the spindle 
moves easily and freely for half a turn, 
and then binds and becomes stiff in its 
movements, it shows that spindle and 
bearing are not round and true. This is a 
very bad defect, and it can be detected 
only in the way we have pointed out, viz., 
by throwing off the band, tightening the 
bearings of the spindle, and turning the 
latter by hand. So long as the band is on, 
especially if it be pretty tight, the spindle 
will be held down so that it will show no 
shake to the hand ; but the moment it is 
used for work, and the chisel is applied to 
the article that is to be turned, the band 
becomes unequal to the task of holding it 
down, the piece that is being turned will 
jump, and the work will be untrue. All 
j this shows itself when the band is no 
longer in place to keep the spindle down 
and make it run appai^ently time. In a 
well-made lathe you may tighten the bear- 
ings of the spindle until you can hardly 
turn it, and still you will find that it 
moves without any perceptible difference 
throughout the entire revolution. 
The fly-wheel next demands our atten- 
tion. The temptation to make this part 
very light, and thus save material, is 
strong, but when yielded to, it works noth- 
ing but evil for the purchaser. In very 
light lathes the fly-wheel and treadle may- 
be built on the sewing-machine plan, and 
indeed an old sewing-machine stand some- 
times answers very well for a very light 
bench-lathe. In this case the fly-wheel 
may be light, because it is driven on both 
the upward and downward motion by the 
foot— the treadle being so arranged that 
the foot rocks instead of having a clean 
sweep up and down. But it is impossible 
to get much power in this w^ay, and in 
most lathes the treadle is so made that 
the foot moves up and down, and the fly- 
wheel is driven only through half a revo- 
lution, the other half being accomplished 
by its own momentum. If, tharefore, the 
fly-wheel has not weight enough to carry 
it round with a speed almost as great as 
that wdiich it takes on the down stroke of 
the foot, the motion will be variable, and 
the w^ork will be untrue. The only w^ay to 
secure equable motion in the fly-wheel, is 
by weight ; see, therefore, that it has it. 
Some of our readers may, however, 
already owm a lathe with a very light fly- 
wheel. This may be remedied by wra];- 
ping the arms with lead, or by screwing 
blocks of metal to the wheel. The young 
workman will, of course, see that this ad- 
ditional metal is so distributed that the 
wheel is not made heavier one side than 
on another, and he will also take care that 
the extra material is so firmly secured 
that there is no danger of its flying off. 
