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.] 
