axle of a wheel, which the clock-work keeps in a state of constant
rotation, and the other end is concealed in a vessel, designed to
represent a reservoir or basin. The continual rotation of the twisted
glass produces the appearance of a progressive motion, as already
explained, and a stream of water continually appears to flow from the
fountain into the basin.

_Facility of Swimming._

The lighter the body is in relation to its magnitude, the more easily will
it float, and a greater proportion of the head will remain above the
surface. As the weight of the human body does not always bear the same
proportion to its bulk, the skill of the swimmer is not always to be
estimated by his success; some of the constituent parts of the human body
are heavier, while others are lighter, bulk for bulk, than water. Those
persons in whom the quantity of the latter bear a greater proportion to
the former, will swim with a proportionate facility.

_Common Mistake in Cooling Wine._

When ice is used to cool wine, it will be ineffectual if it be applied, as
is frequently the case, only to the bottom of the bottle; in that case,
the only part of the wine which will be cooled is that part nearest the
bottom. As the application of ice to the top of the bottle establishes two
currents, upwards and downwards, the liquid will undergo an effect in some
degree similar to that which would be produced by shaking the bottle. If
there be any deposit in the bottom whose weight, bulk for bulk, nearly
equals that of the wine, such deposit will be mixed through the liquid as
effectually as if it had been shaken. In such cases, therefore, the wine
should be transferred into a clean bottle before it is cooled.