86 
THE YOUNG SCIENTIST. 
its loftiest peak, rising to a height of 21,000 feet, 
and bearing on its apex a minute crater. Other 
peaks, though hot so high, are, nevertheless, of 
extraordinary height and steepness: Hadley 
(87) is 15,000 feet; Bradley (89) is 13,000 feet; 
and Wolf (92) is 11,000 feet. The gradual en- 
trance of the summits into sunshine, about the 
First Quarter, is a glorious spectacle, and their 
projection beyond the darkness, thrusting their 
high heads through the blackness below, and 
receiving the golden rays of the sun, give them 
the appearance of golden islands in a sea of ink, 
which may be seen by a keen eye, and which 
probably first gave rise to the idea that the 
Moon was mountainous. An idea of the abrupt- 
ness of this range may be formed from the fact 
that its shadows do not disappear until a few 
hours before the full. It contains but very few 
craters, and consists of ridges and peaks. Upon 
the southwestern border of the Sea of Vapor (L), 
and passing through the well-known crater 
Hyginus (93), is the canal of Hyginus, indicated 
upon the map. It can be seen with a power of 
40 under any moderate-sized objective. It be- 
gins at the foot of a long low hill, as a flat valley 
about 1| miles wide and 9 miles long, contract- 
ing to about one half that width, with steep 
sides and great depth ; passes by four minute 
craters and ploughs its way through the massive 
walls of Hyginus, and throwing up w^alls upon 
either side upon the inside of the crater. Here 
it bends and begins to grow shallow. It was 
just north of Hyginus that Dr. Hermann J. 
Klein, of Koln, discovered a new crater about 
ten years ago. The discovery was confirmed 
by all the leading astronomers of Europe and 
America. Hence, the Moon is not a " dead 
world," but still liveth, though undoubtedly 
very near its end. 
Penn Yan, N. Y. 
Filing Flat and Other Surfaces. 
(Concluded from page 15 J 
One of the chief obstructions to filing a 
flat is that the natural action of the hand and 
elbow are in circular lines. This occurs, as 
will be seen from the joints of the limbs in action 
being the centre of motion. It is to overcome 
this that the careful training of the hands is re- 
quired to enable a flat surface to be filed. The 
amateur or mechanic, whichever it is, must be 
careful in the selection of his file-handles ; they 
should be in proper proportion, not too large and 
not too small. Now here is a point upon which 
scarcely two men agree. Some like a large, 
bulky handle : others prefer a smaller, but one 
with less curve in it ; so this must be left for the 
operator to ^uit his own taste. I have many 
times seen a man take a piece of chisel-rod that 
happened to be near him, and simply stick the 
file into it. This is decidedly wrong ; it shows a 
slovenly workman, to begin with, and is exceed- 
ingly dangerous, as a file is likely to slip out of 
such a temporary thing, and if it should do so, 
the consequences may be most serious. The 
best description of handles are those made from 
the softer kinds of wood, and they should have 
strong iron or brass ferules round the ends into 
which the tang of the file is driv(>n. The shank 
or tang of the file is made in a taper form, and 
should be well fitted into the handle by means 
of a router, which is made in a similar shape 
and cut across like a float, which instrument 
(the float) is used by cabinet-makers. This need 
not be hardened, as it is only used to cut soft 
wood. It is made with a shank to hold in the 
vice, the handle to be cut out is to be held in the 
hand ; a few thrusts to and fro will cut out the 
inside to the shape of the tang of the file. This 
done, the shank is then driven into the handle, 
but not clean up to the end, as if this occurs, the 
file will be likely to soon drop out of the handle. 
From this cause we once had a man whose left 
foot was pinned to the floor by the file, a heavy 
one, falling straight down out of its handle. 
This fact induces me to ask all intending vice- 
men to pay particular attention to the handling 
of their files. Many other w^ays have been re- 
sorted to, to open the handle to fit the shank, 
such as making a piece of iron of a correspond- 
ing shape red-hot, and burning out the hole. 
This is bad, as it chars the inside, renders it less 
likely to wear than anything, and also causes it 
to slip up all ways. There are also many Slov- 
enish ways and means of making shift * * * * 
Learn to keep your vice clean, and your files in 
a row neatly arranged, and when taking into 
use a new set of files, mark one side and reserve 
the side so denoted for purposes that require an 
extra sharp edge. Again, have a set of files for 
different metals. As I have said, when they will 
not cut brass well, they may be used for iron and 
steel, and will be quite as good as new ones ; but 
if used upon cast-iron or steel, they will be of 
no use whatever for brass. In cast-iron es- 
pecially the scale is fatal to a good file, there- 
fore, see that the sand and rough parts are 
well rubbed off with any old worn-out file. 
There are many different ways of finishing vice- 
work ; some draw-file a long piece, which is done 
by placing the file across the work at right 
angles, and with both hands draw it backwards 
and forwards. Much practice is required to do 
this effectually, and if not properly done, the 
marks left from the file, instead of being in a 
straight line, will be across the corners, and 
when finishing work it is a troublesome job to 
