THE YOUNG SCIENTIST. 
37 
large number of customers. Undoubtedly 
the most perfect system of foretelling what 
the weather will be is that now in use by 
the United States Signal Service. The 
prognostications made by this system de- 
pend upon the observations of a very large 
corps of assistants scattered over the entire 
country. From the reports of these assist- 
ants as to the temperature, pressure, and 
hygrometric or moist condition of the at- 
mosphere, and the direction and velocity of 
the wind at different points, tolerably reli- 
able conclusions are reached as to the pro- 
bable character of the weather during the 
succeeding twelve hours at any given sta- 
tion. Absolute certainty is, of course, im- 
possible, and the published results have 
been given as '* Probabilities " and "Indi- 
cations." 
But what neither " Old Probabilities " or 
"Young Indications" would venture to as- 
sume, is now fearlessly claimed by the ad- 
vertisers of a very old and worthless device 
which has been recently manufactured in 
enormous quantities and sold at exorbitant 
prices, chiefly to farmers. We refer to the 
old weather-glass, consisting of a glass 
tube, filled with a solution of camphor and 
sal ammoniac in alcohol — and tightly sealed. 
Under certain conditions of pressure and 
temperature this solution becomes cloudy, 
and when these conditions change, it again 
becomes clear. Unlike a good barometer, 
it is easily made, not costing over ten or 
twelve cents when made in quantity, and 
when mounted in a cheap frame, with a 
twenty- five cent thermometer, it is sold for 
from one to two dollars. 
In its very best form it was carefully in- 
vestigated some years ago by several very 
able scientific men, and shown to be per- 
fectly worthless. It is, in short, a worthy 
companion to the old almanacs, which pro- 
fessed to foretell, months and years ahead, 
just what the weather would be on any given 
day. It is generally advertised as a signal 
service harometer, but it is not a barometer 
in any sense of the word. It has more of 
the character of a rude thermoscope, or heat 
indicator, but as the walls of the glass tube 
are thin, they yield when the pressure of 
the atmosphere varies, and the solubility of 
the salts are somewhat afi'ected by this fact. 
It is therefore a sort of nondescript, to 
which no really correct name can be ap- 
plied. 
It has been advertised largely in the agri- 
cultural papers, and has doubtless been sold 
extensively to farmers, having been freely 
praised, even by those papers that make a 
virtue of decrying all humbugs. And yet a 
more thorough and dangerous humbug has 
rarely been brought before the people, sim- 
ply because it has all the appearance, with- 
out any of the reality of honesty. 
We therefore add it to the Lefevre Dia- 
monds and the Dollar Watch with "steel 
works," described in previous issues. In 
our next we shall take up a fourth humbug 
of a scientific or a mechanical kind. These 
so-called scientific humbugs are the most 
dangerous to the community, and the safest 
to the originators, and we propose to pay 
our respects to them seriatim. 
Making Glass Apparatus. 
By Eomtn Hitchcock. 
Few things will give the young scientist 
more satisfaction than a set of instruments of 
his own make. Some of the most useful and 
interesting pieces of apparatus are made of 
glass, and therefore a few practical directions 
for working in this material will doubtless be 
acceptable. 
We must caution our readers, however, that 
success in this work requires a certain dex- 
terity which cannot be attained without a con- 
siderable amount of patience and persever- 
ance. Failure at first is almost inevitable, but 
much of the difficulty vanishes when one has 
become accustomed to the handling of glass 
tubing, and has acquired the knack of heating 
and bending without fear of fracture and of 
blowing small bulbs on the end. 
We must have a spirit lamp, or, what is far 
better, if gas can be used, a Bunsen barner, 
and for blowing glass we should have a good 
blowpipe worked by the foot, although a Bun- 
