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ANNIVERSARY ADDRESS 
of nature’s laws respecting this matter. A person of even moderate 
intelligence can open a window or a door where a draught will 
injure no one. In an average household some of the members 
will have sufficient knowledge to enable them, at any considerable 
gathering of persons where perhaps also many air-consuming lights 
are burning, to distribute the air from open windows by aid of 
curtains so judiciously disposed as to allow of the entrance of the 
maximum amount of air with the minimum of draught. Perhaps 
the best form of ventilator is the old tube reintroduced by Tobin ; 
a wooden or zinc tube a few inches broad, several inches wide, 
and about live feet long, placed in any more or less out-of-sight 
place in the room, the bottom end communicating with the external 
air by a similar, generally very short transverse tube carried 
through the wall. Such tubes may vary in size, or two or more 
may be used in large rooms. They really are inverted syphons, 
the slight warmth of the inside of the room above the outside 
enabling them, by well-known natural laws, continuously to carry 
inwards a current of air which quietly breaks in a fan-like manner 
into the upper part of the room above the heads of the occupants, 
a continuous change of air without a draught resulting. Window- 
sashes may be arranged on a similar principle but with less effect. 
According to the number of occupants of the room, each tube 
should, at its upper extremity, be closed, or partially closed, by 
a lid, or be left quite open. Even these tubes, therefore, need a 
little intelligent management. In short, the extent to which a 
room may be fairly successfully ventilated depends on the extent 
to which some one or more of its occupants realises and applies the 
natural principles involved. A proper supply of pure air to our 
dwellings can never be obtained merely by ventilators or other 
mechanical contrivances, it must always depend upon intelligence 
and knowledge. 
The avoidance of extreme heat in summer and extreme cold in 
winter in our habitations is a matter of considerable importance as 
regards our comfort, and not inconsiderable as regards our health. 
Here experience guided by intelligence helps us much, while the 
natural laws which govern the matter are not at all obscure. A 
room which in summer has become pleasantly cool during a night 
may be kept cool until it is wanted, if blinds, curtains, and shutters 
are closed over the windows, and the door or doors not left open. 
Eor, convection of heat to the walls of the room by currents of hot 
air from without is thus avoided, diffusion between the hot air 
without and the cold air within is retarded, while any direct 
rays of heat from the sun are excluded. With a little light 
