nce:
The water at the head of a weir is passing every instant from
slower into quicker motion; but (until broken in the air) the fast
flowing water is just as dense as the slowly flowing water. But a
fan alternately compresses and rarefies the air between it and the
cheek, and the violence of a destructive gust in a gale of wind
means a momentary increase in velocity and density of which I
cannot myself in the least explain,--and find in no book on
dynamics explained,--the mechanical causation.

The following letter, from a friend whose observations on natural
history for the last seven or eight years have been consistently
valuable and instructive to me, will be found, with that subjoined
in the note, in various ways interesting; but especially in its
notice of the inefficiency of ordinary instrumental registry in
such matters:--

"6, MOIRA PLACE, SOUTHAMPTON, _Feb. 8th, 1884_.

DEAR MR. RUSKIN,--Some time since I troubled you with a note or two
about sea-birds, etc.... but perhaps I should never have ventured
to trouble you again, had not your lecture on the 'Storm Clouds'
touched a subject which has deeply interested me for years past. I
had, of course, no idea that you had noticed this thing, though I
might have known that, living the life you do, you must have done
so. As for me, it has been a source of perplexity for years: so
much so, that I began to wonder at times whether I was not under
some mental delusion about it, until the strange theatrical
displays, of the last few months, for which I was more or less
prepared, led so many to use their eyes, unmuzzled by brass or
glass, for a time. I know you do not bother, or care much to read
newspapers, but I have taken the liberty of cutting out and
sending a letter of mine, sent on the 1st January to an evening
paper,[A] upon this subject, thinking you might like to know that
one person, at any rate, has seen that strange, bleared look about
the sun, shining so seldom except through a ghastly glare of pale,
persistent haze. May it be that the singular coloring of the
sunsets marks an end of this long period of plague-cloud, and that
in them we have promise of steadier weather? (No: those sunsets
were entirely distinct phenomena, and promised, if anything, only
evil.--R.)

I was glad to see that in your lecture you gave the dependants upon
the instrument-makers a warning. On the 26th I had a heavy
sailing-boat lifted and blown, from where s