, published by the Society for Promoting Christian Knowledge, a
curious and simple experiment is described, whereby the existence of
upper and under currents of air and the action of land and sea breezes
may be clearly seen and understood. We quote the passage:--

"The existence of the upper and under currents of air which mark the
phenomena of the trade-winds, and of land and sea breezes, may be
beautifully illustrated in two adjoining rooms, in one of which a good
fire is burning, while in the other there is none. If the door between
the two rooms be thrown open, the cold air will enter the heated room in
a strong current, or, in other words, as a violent wind. At the same
time the heated air of the warm room ascends and passes the contrary way
into the cold room, at the upper part of the same doorway; while in the
middle of this opening, exactly between the two currents, the air
appears to have little or no motion. The best way to show this
experiment is to introduce the flame of a candle into the doorway
between a hot and a cold room. If the flame be held near the bottom of
the doorway, where the air is most dense, it will be strongly drawn
towards the heated room; and if held near the top of the door it will be
drawn towards the cold room with somewhat less force; while midway
between the top and bottom the flame will be scarcely disturbed.

"There is also another pretty experiment which illustrates well the
theory of land and sea breezes. Take a large dish, fill it with cold
water, and in the middle of this put a water-plate or a saucer filled
with warm water. The first will represent the ocean, and the latter an
island made hot by the rays of the sun, and rarefying the air above it.
Take a lighted wax candle and blow it out; and, if the air of the room
be still, on applying it successively to every side of the saucer, the
smoke will be seen moving towards the saucer and rising over it, thus
indicating the course of the air from sea to land. On reversing the
experiment, by filling the saucer with cold water (to represent the
island at night) and the dish with warm water, the land breeze will be
shown by holding the smoking wick over the edge of the saucer; the smoke
will then be wafted to the warmer air over the dish."

We have just tried the first of these experiments, with complete
success. We would, however, recommend a piece of twisted brown paper,
lighted and blown out, instead of a wax candle, beca