78 
HARDEN MECHANICS. 
desired to shift the specimen, or examine the roots, the drain-cup 
is placed on the top of a stout block of wood, as shown in the 
cut, and by pressing the pot downwards the entire hall of earth 
which it contained is, as it were, elevated to the view, and may 
then he removed with every facility, and without so much as 
agitating a leaf of the plant. The contrivance cannot fail to be 
properly estimated by all interested. It is called the West Kent 
Garden Pot, and was registered on the 6th of February of the 
present year. 
Another highly useful instrument to all who have the manage¬ 
ment of stoves or early forcing-houses, with greater pretensions 
to a scientific character, has also, in the course of the past month, 
been presented to the public, in the hygrometer of Mr. Simmons. 
A ready means of ascertaining the amount of moisture contained 
in the atmosphere of houses of this kind has long been a deside¬ 
ratum. The thermometer gives us the temperature with suffi¬ 
cient exactitude for any practical purposes ; but it is well known 
to gardeners that successful results do not depend alone on the 
elevation or depression of temperature. To form a genial atmo¬ 
sphere, in which vegetation will proceed with the desired vigour, 
it is essential that a due proportion of aqueous particles be pre¬ 
sent ; an elevated arid atmosphere, instead of affording nourish¬ 
ment to the plants, is actually exercising the directly opposite 
influence, by depriving them of the moisture of their systems so 
necessary to their existence. This is a truism, but of infinite 
importance. That all heating apparatuses, with the exception of 
the tank system, have a tendency, in the rarefaction of the air, 
to abstract its moisture, is also known, and hence the practice of 
throwing water on the paths and stages to meet the demand thus 
occasioned; this, however, in the absence of a registering me¬ 
dium, is but a haphazard method of maintaining the equilibrium 
of the atmosphere, which must frequently be loaded with vapour 
to saturation, and again be dry as the parching plains of a de¬ 
sert : presenting fluctuations that cannot be other than injurious 
to the plants which are subject to them. To obviate these bale¬ 
ful influences the hygrometer of Mr. Simmons is a powerful 
agent; for with its assistance it is as easy to preserve any required 
amount of moisture, as with that of the thermometer it is to regu¬ 
late the temperature. 
