In consequence of the absence of passive
resistances, motion occurs without any stress, and almost mechanically,
giving air not only to him who is actuating the fan, but also to his
vis-a-vis.
Fig. 2 represents an apartment apparatus designed to be placed in front
of a table or desk, in order that one can fan himself while eating or
writing. Being mounted upon casters, it can be readily moved about from
one place to another. At the extremity of a wooden support, whose height
may be varied at will, there is arranged a flexible fan whose handle is
fixed near a pulley. A small piece of lead forms the counterpoise of the
fan, which is thus completely balanced. Over the pulley runs a cord, each
end of which is attached to a pedal. It will be seen that the alternate
motion of these pedals must cause a rotation of the pulley in one
direction or the other, and that consequently the fan will rise or fall
more or less rapidly, and give a quantity of air that varies according to
the rapidity with which the toes are moved.--_La Nature_.
* * * * *
PUNKAS.
[Footnote: Extract from a lecture recently delivered at Bombay.]
By J. WALLACE, C.E.
The function of a punka is to cause a current of air to pass the human
body so that the animal heat may escape more rapidly. This has nothing to
do with ventilation; for if the punka were used in a closed room, it
would still produce a cooling effect on the skin.
Pages:
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68