THE YOUNG SCIENTIST. 
55 
Simple Hints for Beginners. 
NO. I. 
WE propose to give, from time to time, 
such simple elementary instructions 
in regard to the use of the microscope as 
will smooth the path of those who are com- 
mencing the study, and whose instruments 
are not of the best quality. It is all very 
well to say ** don't buy a poor microscope;" 
suppose the reader has one of this kind 
already, and cannot afford to buy a better 
one — is it not better to work with a poor 
instrument than not to work at all? By 
keeping carefully within the bounds of 
what such an instrument can accomplish, it 
is wonderful how much it will show us. 
One of the first things to be learned is 
the art of getting the object well illumin- 
ated. We must remember that the micro- 
scope is, after all, only an addition to the 
eye, and as the eye sees only by means of 
light, unless plenty of light passes from the 
object to the eye, we cannot see it. At the 
same time, we must avoid a mistake of ex- 
actly the opposite kind, and avoid getting 
too much light. The diflaculty of reading 
letters which are written or engraved on 
bright metal strongly illuminated, shows 
the necessity for properly adjusting the 
amount of light to the circumstances of the 
case. As a general rule, the higher the 
magnifying power used, the greater is the 
amount of light required. With low 
powers — twenty to fifty diameters — even the 
cheapest compound microscopes will work 
with very moderate light. 
The necessity for proper illumination is 
felt more in using the simple microscope 
than in any other. With very low powers, 
it is true, it is not difficult to see almost any- 
thing, but when the focal length of the lens 
is less than half an inch, it requires some 
care to prevent the frame of the glass or 
some part of the person, from shading the 
object, and in that case it will be impossible 
to see clearly. If the reader will carefully 
watch either his own movements, or that of 
a friend who is examining some opaque 
object with a simple microscope, he will | 
soon see how want of care and skill in thi» 
respect prevents complete success. When 
the difficulty is once pointed out, however, 
it is easy to avoid it, and then we will be 
astonished at the wonderful improvement 
that our lens has undergone. 
By means of good illumination, it is easy 
to see, with a power of ten diameter s» 
things, which, with slightly inferior illumin- 
ation, are quite invisible with a power 
of twenty-five. Indeed, good illumina- 
tion will often supersede the necessity for 
a magnifier, and dissections and similar 
operations may be carried on better with 
the naked eye than with a lens. To prove 
this it is only necessary for the beginner to 
examine such objects as eels in vinegar or 
in paste. Place a drop on a slide, and look 
at it, without special illumination, holding 
it so that the ground or any dark surface 
may form the background. No eels will be 
seen. Now hold the slide against the light, 
and somewhat obliquely, and the eels will 
be quite distinct. 
In the above case the objects are trans- 
parent, that is to say, we look through them> 
but the principle applies equally to opaque 
objects, or objects which we look aU Sup- 
pose we have a few portulacca seeds, one of 
the most beautiful objects that can be 
found. If we look at them through a cheap 
compound microscope — having merely laid 
them on a dark ground — they will be almost 
invisible. But if we throw on them a strong 
light, by means of a condensing lens, they 
will show with great beauty, even with a 
cheap non-achromatic microscope. 
To he continued. 
Trichina. 
FKOM several parts of the country there 
come to us reports of sickness and 
death, caused by the presence of these par- 
asites. A gentleman who has been inves- 
tigating the subject carefully, reports a very 
large percentage of the ham and pork in 
the New York market as being infected with 
trichina. Trichina are easily detected by 
means of a microscope of low power. The 
