THE YOUNG SCIENTIST. 
39 
wards, as you find most convenient. You 
want to grind the face of the tool so that 
it has one smooth face, not a number of 
little facets ; and keep your pressure so 
that you do not grind away the point 
faster than the part near the top or back 
of the tool. If you are successful in al- 
ways holding your tool properly, you will 
not have much occasion for a small grind- 
stone. But one will be useful in grinding 
the upper part of the face, which being- 
wider than the point, takes longer time to 
grind off, on your oilstone. But be care- 
ful how you use a grindstone ; you do not 
need it for sharpening your tools at the 
point ; that is best done on the oilstone. 
A final polish is given to the tools by the 
use of a leather strop. 
To engrave well it is necessary to keep 
the tools well faced, and keenly sharp. 
The face of the tool should be rather long 
than short. If too obtuse it plows its way 
/ 
Fig. 11. 
Fig. 12. 
in the wood, rather than cuts it, and the 
shaving will also turn over at the point, 
and prevent the engraver seeing the line 
that is cut. Fig. 11 shows a tool too ob- 
tuse. But a tool of about the angle shown 
in Fig. 12 will cut cleanly, and the shav- 
ing will fall out so that it will not obstruct 
the sight of the engraver. 
A soft brush (a tooth brush is good) is 
useful to brush away the small chips from 
the block. It must be soft, so as not to 
injure the lines of the engraving. 
Learning to Use the Microscope— I. 
A S it is always well to begin at the be- 
ginning, it may not be out of place to 
give a few hints to those who have just 
purchased an instrument. When a micro- 
scope is first brought home, the purchaser 
is in general in a great hurry to examine 
it, and in this case especially the old pro- 
verb holds true, "The more hurry the 
^ worse speed." The first thing to be done 
is to carefully unpack the instrument, and 
see that the "articles which accompany it 
correspond with the bill. . In unpacking. 
i beware of using any undue violence. Re- 
j move the packing material, but do not 
throw it away until you are satisfied that 
no little loose piece or accessory has got 
mixed with it. Then lift the microscope 
carefully out of its case. This should re- 
quire no unusual force ; a little patience 
will bring all right, whereas if you push 
and press, some part will very likely get 
bent or perhaps broken. 
The next step is to free the instrument 
from dust, for no matter how well it may 
have been protected, dust will almost 
always penetrate during the shaking 
which occurs during travel. Dust is most 
easily removed by means of a soft camel 
hair pencil. Wiping with coarse or dusty 
cloths will infallibly scratch and injure 
the glasses. 
We are now ready to begin the use of 
the microscope, and here, as in most other 
studies, "it is the first step that costs. " 
After we have once made a beginning, it 
is easy to improve our skill and know- 
ledge; the difficulty is to make the be- 
ginning. 
It is always best for the beginner to 
commence with objects which are already 
mounted, and which consequently reqviire 
no preparation to fit them for examina- 
tion. It is well, therefore, to order half a 
dozen or more objects with the micro- 
scope, so that the material for prelimin- 
ary practice may be at hand. The list 
should include such objects as require the 
most dissimilar methods of handling and 
illumination. Thus, for example, it should 
include the simplest transparent objects ; 
objects that can only be examined by re- 
flected light, and that require good illum- 
ination ; objects that have finely marked 
surfaces, etc., etc. A list which will be 
found very interesting, which are easily 
procured, and which will give the be- 
ginner good practice, are : 1, a section of 
wood (either stained or colorless) mounted 
in balsam ; 2, a piece of a butterfly's wing 
for examination as an ojmque object ; 3, 
a section of pith of plant, mounted dry, 
and which can be examined either as an 
opaque object or as a transparent one ; 
4, butterfly's scales, detached from the 
wing ; 5, wing of a mosquito ; 6, diatoms: 
To be continued. . •• 
