THE YOUNG SCIENTIST. 
95 
ally refused, until the universal noise-mak- 
ing of the Fourth of July comes to rein- 
force his demands, and notwithstanding all 
that has been said or written about the 
dangers of pistols or cannons, every Fourth 
brings an enormous number of serious and 
fatal accidents. 
Now, if instead of endeavoring to stifle 
the fondness for firearms, parents and 
guardians would endeavor to guide the taste 
of boys in this direction, it would be much 
more sensible. The boy who is in the 
habit of using firearms for sport or for 
marksmanship will never degrade them to 
the mere purpose of making a noise. By 
most persons, however, the most dangerous 
and foolish course is in general pursued 
toward the lad who shows an inclination to 
use the gun, particularly if his guardian be 
not himself a sportsman. When a boy first 
asks permission to use a gun, it will be 
found that most old women (whether they 
wear petticoats or not) forbid the use of 
what they consider such a dangerous wea- 
pon, but are willing that he should have a 
pistol^ — which is a far more dangerous play- 
thing, both for the boy himself and for 
lihose who are about him. The long barrel 
of a gun is not readily pointed either in the 
direction of ourselves or others, without 
our knowing it; while the shorter pistol 
frequently comes into dangerous range 
■either of the person who holds it or of 
others, without being immediately per- 
<jeived. Moreover, a boy in such circum- 
stances receives no proper instruction in 
the handling, loading, carrying, and dis- 
charging of a gun, when by his own stealth 
or the carelessness of his guardians, he 
comes into possession of one. Those rules, 
which, from long habit, have become second 
nature to all good sportsmen, are unknown 
to him, and of course unacted upon. He 
carries his gun with the hammers on the 
caps, and with the muzzle pointing down- 
ward or horizontally toward every point of 
the compass. He pokes the muzzle through 
any fence he may have to cross, gets 
through or over himself as best he can, and 
then drags the gun after him, frequently 
receiving the contents of one of the barrels 
while so doing. In short, his gun, instead 
of being an instrument of honest recrea- 
tion, becomes the source of stolen sprees, 
and is sooner or later a cause of serious ac- 
cident. Sensible guardians ought to aban- 
don all this. If a young man shows an 
inclination for the sports of the field, let 
them see that he is provided with a safe 
and ejfficient weapon, and carefully in- 
structed in its use. Youth must have re- 
creation, and it is better for a young man 
that he should devote his days to the green 
fields than his nights to the green table. 
New Photographic Process for Copy- 
ing Drawings. 
The following is a convenient method for 
reproducing drawings, plans, maps, and line 
engravings in general. The paper is first pre- 
pared by dipping it in a bath composed as fol- 
lows: Distilled water, 10 ounces; perchloride 
of iron, 1 ounce; oxalic acid, 4 drachms. 
When dry, the paper, if protected from light, 
can be kept as long as may be necessary. To 
copy a drawing, the model, on oiled or trans- 
parent paper, is applied on some paper thus 
prepared, and the whole exposed to light in an 
ordinary photographic printing press. In sum- 
mer and in the sunlight, an exposure of from 
fifteen to thirty seconds is sufficient; in winter, 
forty to seventy seconds; in the shade, during 
clear weather, from two to six minutes; and, 
lastly, when the weather is overcast, cloudy, 
rainy or snowy, from fifteen to forty minutes 
are necessary. 
The paper, on being withdrawn from the 
press, is placed in a bath containing from fif- 
teen to eighteen per cent of ferrocyanide of 
potassium. It is then washed in an abundance 
of water, passed in a bath containing eight or 
ten per cent of muriatic acid, washed again, 
and dried. 
The explanation of the operation is as fol- 
lows: The perchloride of iron, under the in- 
fluence of light, is reduced by oxalic acid to 
the state of protochloride, which is soluble in 
a solution of ferrocyanide of potassium, while 
