THE yOUNG SCIENTIST. 
31 
the core has been taken out, but to make 
the inside quite smooth and polished, as 
upon this the beautiful transparency of a 
well-made powder horn chiefly depends. 
Consequently, while we may use files and 
riffles for the beginning of the work, we 
must soon give them up for a steel scraper 
made out of a bar or rod of steel, of which 
the end has been bent square and properly 
ground and sharpened. The edge of the 
scraper should be very sharp and finely 
finished on an oilstone. It will not do, 
however, to depend upon the scraper alto- 
gether, as this tool is very apt to work the 
material into ridges or utters as they are 
called. Bent files, called riffles, must be 
used for straightening the surface, and the 
scraper must be confined to its proper 
office of smoothing. The same process 
must also be applied to the outside, which 
must be worked down until the surface is 
perfectly even. 
In the meantime care must be taken to 
leave the lower end of the horn so thick 
that a groove may be cut in it to receive 
the bottom. In the common horn flasks 
the bottom is made of wood simply fas- 
tened with tacks or screws, but this makes 
an unsightly finish. The proper way is to 
cut a circle or disk of horn out of a flat 
piece, and fasten this in a groove, which is 
done as follows : The end of the horn 
having been cut off square and even, a 
groove is cut round the inside at a very 
short distance from the edge— say one- 
eighth of an inch. To cut the end square 
take a piece of paper with a straight edge, 
wrap this round the horn, mark the line 
with a fine pencil, and cut off the horn 
with a fine, sharp saw. The edge is made 
perfectly smooth and straight by means of 
a small plane, for which purpose the 
little cast-iron planes, now so common, 
are excellent. The groove is cut by means 
of a tool like a cooper's croze or carpen- 
ter's marking gauge. The gauge has, in- 
stead of a point, a hook-shaped cutter, 
which cuts a clean but not very deep 
groove round the inside. The flat disc is 
then turned up in the lathe so as to have 
a ridge on the edge, this ridge just fitting 
the groove. The disc is made a very little 
larger than the opening into which it is to 
fit, and the latter is expanded by plunging 
the horn for a few minutes into boiling 
water. The horn softens and expands so 
that the disc is easily forced into its place. 
When the horn cools it shrinks on the 
disc so as to make it very firm. 
Before fastening the disc in its place, 
however, the surface of the disc and the 
inside of the horn should be finely pol- 
ished. This is neccessary for the purpose 
of rendering the flask transparent, for no 
matter how thin the horn may be scraped 
it will not be transparent unless it is finely 
polished. This is seen in glass, very thick 
plates of which are quite transparent 
when the surfaces are polished, but lose 
this quality when the surface has been 
ground or slightly roughened. 
Horn is polished by being first smoothed 
by means of the steel scraper ; then it is 
worked with the finest pumice-stone or 
rotten-stone, and oil or water, a piece of 
leather being used as a rubber ; after this 
it is polished by means of fine, washed 
putty powder mixed with water or oil, and 
rubbed on with cloth or leather. The very 
finest finish is given by rubbing with the 
naked hand in the same way that tortoise- 
shell and papier mache are polished. 
After the inside has been polished and 
the bottom fastened in, the projecting 
edge of the horn is rounded and the entire 
outside is polished by the same process 
that has been described for the inside. 
Previous to the polishing of the outside, 
the mountings should be carefully fitted 
to their places, and in the case of horns 
which are not cut off pretty well down, the 
outside should be polished and the rings 
riveted on before the bottom is put in, as 
it will be impossible to do it afterwards. 
When a spring top is to be attached the 
opening will be large enough to allow of the 
riveting of the rings after the bottom has 
been fastened and the horn polished. No 
grooves should be cut for the rings. They 
should simply be driven on tightly and 
fastened with one or two very slight rivets. 
The top may be screwed on, or fastened 
in any other way that will make a good 
job. As, however, our object is to tell how 
to work horn, it is unnecessary to describe 
them. In our next article we will tell 
how to work horn into other forms and ar- 
ticles. 
