Clocks have been proposed and made with this object, by
which a sheet of paper is moved, slowly and uniformly, before a
pencil fixed to a float upon the surface of the mercury in the
cup of the barometer. Sir David Brewster proposed, several years
ago to suspend a barometer, and swing it as a pendulum. The
variations in the atmosphere would thus alter the centre of
oscillation, and the comparison of such an instrument with a good
clock, would enable us to ascertain the mean altitude of the
barometer during any interval of the observer's absence.(3*)
An instrument for measuring and registering the quantity of
rain, was invented by Mr John Taylor, and described by him in the
Philosophical Magazine. It consists of an apparatus in which a
vessel that receives the rain falling into the reservoir tilts
over as soon as it is full, and then presents another similar
vessel to be filled, which in like manner, when full, tilts the
former one back again. The number of times these vessels are
emptied is registered by a train of wheels; and thus, without the
presence of the observer, the quantity of rain falling during a
whole year may be measured and recorded.
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