it securely in, winds up the clock-work, puts
out his yellow light and lets in the sunshine.
His lanthorn glass is yellow, because the
yellow rays are the only ones which can be
safely allowed to fall upon the photographic
paper during its removal from the instrument,
to the dish in which its magnetic picture is to
be fixed by a further chemical process. It is
the blue ray of the light that gives the
daguerrotypic likeness;—as most persons who
have had their heads off, under the hands of
M. Claudet, or Mr. Beard, or any of their
numerous competitors in the art of
preparing sun-pictures, well know.

Since the apparatus of Mr. Brooke for the
self-registration of the magnetic changes has
been in operation at Greenwich, the time of
Mr. Glaisher and his assistants has been
more at liberty for other branches of their
duties. These are numerous enough.
Thermometers and barometers have to be watched
as well as magnets. To these instruments
the same ingenious photographic contrivance
is applied.

The wooden building next to the magnet-
house on the south-west contains a
modification of Mr. Brooke's ingenious plan, by
which the rise and fall of the temperature of
the air is self-registered. Outside the building
are the bulbs of thermometers freely exposed
to the weather. Their shafts run through
a zinc case, and as the mercury rises or falls,
it moves a float having a projecting arm.
Across this arm is thrown the ray of prepared
light which falls then upon the sensitive paper.
Thus we see the variations of the needle and
the variations in heat and cold both recording
their own story, within these humble-
looking wooden sheds, as completely as the
wind and the rain are made to do the same
thing, on the top of the towers of the
Observatory. The reward given to the inventor
of this ingenious mode of self-registration has
been recently revealed in a parliamentary
paper, thus:—' To Mr. Charles Brooke for
his invention and establishment at the Royal
Observatory, of the apparatus for the self-
registration of magnetical and meteorological
phenomena, 500l.' Every year the invention
will save fully 500l. worth of human toil;
and the reward seems small when we see
every year millions voted for warlike, sinecure,
and other worse than useless purposes.

Photography, however, cannot do all the
work. Its records have to be checked by
independent observations every day, and then
both have to be brought to their practical value
by comparison with certain tables which test
their accuracy, and make them available for
disclosing certain scientific results. The
preparation of such tables is one of the practical
triumphs of Greenwich. Many a quiet
country gentleman amuses his leisure by
noting day by day the variations of his
thermometer and barometer. Heretofore
such observations were isolated and of no
general value, but now by the tables
completed by Mr. Glaisher, and published by
the Royal Society, they may all be converted
into scientific values, and be made available
for the increase of our weather-wisdom. For
nearly seventy years the Royal Society had
observations made at Somerset House, but
they were a dead letter—mere long columns
of figures—till these tables gave them
significance. And the same tables now knit
into one scientific whole, the observations
taken, by forty scientific volunteers, who,
from day to day, record for the Registrar-
General of births and deaths, the temperature,
moisture, &c., of their different localities,
which vary from Glasgow to Guernsey, and
from Cornwall to Norwich.

What the Rosetta stone is to the history of
the Pharaohs, these Greenwich tables have
been to the weather-hieroglyphics. They
have afforded something like a key to the
language in which the secrets are written;
and it remains for industrious observation
and scientific zeal to complete the modern
victory over ancient ignorance. Already, the
results of the Greenwich studies of the weather
have given us a number of curious morsels
of knowledge. The wholesale destruction of
human life induced by a fall in the temperature
of London has just been noticed. Besides
the manifestation of that fact, we are shown,
that instead of a warm summer being
followed by a cold winter, the tendency of the
law of the weather is to group warm seasons
together, and cold seasons together. Mr.
Glaisher has made out, that the character
of the weather seems to follow certain curves,
so to speak; each extending over periods of
fifteen years. During the first half of each of
these periods, the seasons become warmer and
warmer, till they reach their warmest point,
and then they sink again, becoming colder
and colder, till they reach the lowest point,
whence they rise again. His tables range
over the last seventy-nine years—from 1771
to 1849. Periods shown to be the coldest,
were years memorable for high-priced food,
increased mortality, popular discontent, and
political changes. In his diagrams, the warm
years are tinted brown, and the cold years
grey, and as the sheets are turned over and
the dates scanned, the fact suggests itself that
a grey period saw Lord George Gordon's
riots; a grey period was marked by the
Reform Bill excitement; and a grey period
saw the Corn Laws repealed.

A few more morsels culled from the
experience of these weather-seers, and we have
done.

Those seasons have been best which have
enjoyed an average temperature—nor too hot
nor too cold.

The indications are that the climate of
England is becoming warmer, and,
consequently, healthier; a fact to be partly
accounted for by the improved drainage and
the removal of an excess of timber from the
land.