THE YOUNG SCIENTIST. 
57 
them. What is true of simple instruments 
is much more true of principles which 
depend upon unusual phenomena. It 
would be a very difficult matter to ex- 
plain to a class the peculiar properties of 
oxygen or chlorine without illustrating 
these properties by experiments, and the 
properties of the air, such as its weight, 
elasticity, compressibility, etc., are but 
feebly apprehended by a class who have 
never seen these properties illustrated by 
experiments. Most teachers dread the 
performance of experiments for two rea- 
sons : Experimentation is always asso- 
ciated with the idea of " mussiness "— 
spilt liquids, clothes burned with acids, 
and general disorder, are, in their minds, 
the unfailing accompaniments of the per- 
formance of experiments. The second 
reason is the dread of failure. 
Dread of failure can be overcome only 
by certainty of success. Let the teacher 
feel that the experiments which he is 
about to perform are certain to succeed, 
and that which was before a dread and an 
annoyance, will become a pleasure. Noth- 
ing is so disheartening as the failure of an 
experiment. Our w^hole course of teach- 
ing has been an effort to impress upon our 
students the uniformity of nature and the 
certainty of obedience to known laws ; 
and now, when we come to test the matter, 
it is found that either nature is fickle or 
we do not understand her. The inference 
against the teacher is, in the minds of 
most pupils, irresistible, and, of course, 
it is natural that teachers should dread 
being placed in such a predicament. The 
way to avoid this is, not by shirking a 
duty, but by qualifying ourselves for the 
performance of it. 
As to the first objection, it should be 
understood that disorder is one of the 
most efficient causes of failure. Show us 
an experimenter whose table is in a 
"muss;" who spills his liquids, knocks 
over his apparatus, and disturbs his pre- 
vious arrangements, and we will show you 
one to whom failure is no stranger. We 
have now in mind a teacher who often 
appears upon the lecturer's rostrum, 
surrounded by apparatus. He, in gene- 
ral, asks and receives very little assist- 
ance from those around him. He per- 
forms his own experiments, and yet we 
have seen him, at the close of a lecture 
involving the use of batteries, jars of 
liquids and gases, hot acids, furnaces, 
etc., with scarcely a speck upon his i)er- 
son or a stain upon his clothes. No spill- 
ing or overturning with him. He seems 
to move about among his apparatus as if 
it were part of himself, and while his lips 
are giving the most beautiful explanations 
of physical phenomena, his hands are 
busily employed in illustrating them. It 
is needless to say that such an exi^eri- 
menter is uniformly " successful. 
Careful study of the principles involved 
in the experiment to be performed, com- 
bined with a little private practice in the 
necessary manipulations, will soon place 
any intelligent young man or woman 
above all dread of failure, and when this 
is the case, experimenting becomes a 
pleasure instead of an annoyance. 
Cheap Lathes and How to Use Them. 
lY. 
CHOICE OF A LATHE. 
THE framing next demands attention. 
See that it is firm and without shake. 
If the different pieces can move on each 
other it will be impossible to do good 
work. Of course, when the bed or shears 
are made of one solid piece of metal, all 
shake of this kind is impossible, so far as 
this part is concerned, but in the lathes 
with wooden shears, which consist of two 
pieces lying parallel with each other, and 
held together at the ends by means of 
bolts and screws, it sometimes happens 
that the bolts get loose, and then there is 
trouble. Some kind of lock nut would be 
the best remedy for this. A lock nut is 
one which, after being screwed up, is 
locked, so that it cannot be unscrewed 
without special means for loosening it. 
As these bolts rarely, if ever, require to 
be taken out after they are once in place, 
a good i)lan is to slightly rivet them if 
they should ever get shaky. 
Although metal shears, cast in one 
piece, cannot get shaky themselves, they 
are frequently fixed to the frame in such 
a way as not to be very firm. The top of 
the frame or support should be broad, and 
