130 The Use of the Hygro-Spectroscope.
few months' practice, the observer will meet with success;
but he must not expect it to be unlimited, although the
spectroscope is more to be relied on, and far in advance of
any other means of presaging rain. For cases occur some-
times in which a high percentage of rain-band has led him to
predict rain, yet that rain did not occur in his immediate
vicinity, but passed—as I have already proved in numerous
cases—to one or other side of him ; in some few instances
the rain-cloud has deposited its shower before passing over
his locality. Everybody knows how localised rain is, and to
state that such a prophecy as I have adduced has proved
incorrect is a most unwarrantable paralogism.
What we really require is a system of well-trained observers
in the British Isles; then our daily forecasts in regard to rain
will begin to show signs of improvement. They sadly want
it, however. For something surely must be expected from an
instrument of such marvellous telescopic power that can
detect a rain-cloud in certain conditions of the atmosphere,
100 miles off, or even more ; and that can partly inform you
of the chemical composition of stars at the distance of billions
and billions of miles.
I would urge all those who take an interest in this
fascinating branch of Dioptrics to use their best endeavours
to promote the adoption of the hygro-spectroscope, particu-
larly amongst farmers and others whose interests are affected
by the weather; but also, if possible, to influence "the
powers that be" to further the adoption of an invaluable
instrument that may be the means of saving the country
annually thousands of pounds.
[Those desiring further information as to the practical
employment of the instrument may be referred to Mr. Cory's
interesting little book, 'How to Foretell the Weather with
the Pocket Spectroscope' (London, Chatto & Windus, 1884),
in which are reprinted the letters to the 'Times' noticed
above.—Ed.]