Ventilation as a dynamical problem : a paper read before the Annual Meeting of the Medical Officers of Schools Association, on February 6th, 1902 / by W.N. Shaw ; with the subsequent discussion.
- Shaw, Napier, 1854-1945.
- Date:
- 1902
Licence: In copyright
Credit: Ventilation as a dynamical problem : a paper read before the Annual Meeting of the Medical Officers of Schools Association, on February 6th, 1902 / by W.N. Shaw ; with the subsequent discussion. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![tlie coM flues afford the most effective and permanent air siipi)ly of a house wlien the windows and basement door are closecl. This mode of suj)i)ly has many advantages. It takes the air from above the roof, where it is free from the impurities of the streets. It is true that the oi)enin^ from which the air is drawn is ])erilously near the oi)eniii‘,^ of chimneys which are deliver- ing smoke, and that in times of fog there is a good deal of smoke mixed with the air. But, on the other hand, the occasional fire in the grate at the foot of the chimney purifies the air channel even more effectively than dusting out a channel exclusively reserved for inlet })urposes, and the layer of soot may act also to some extent as a disinfectant. More- over, the flues are all in the })arty walls, and the cold flue is probably between two, or at least adjoins one that carries away the smoke of an active fire, so that the incoming air is moderately warmed by the time it gets into the rooms. With an allowance of two cold flues to one active fire a very reason- able system of ventilation would be maintained, sutlicient in the aggregate for, say, three persons per fire—a moderate estimate for a London household. VI.—Draughts. As already mentioned, the treatment of ventilation problems by the electrical analogy omits a very important aspect of the (piestion, namely, the distribution of currents in the ventilated space. This is the much discussed (piestion of draughts. In speaking of a discussion upon ventilation at the Sanitary Insti- tute last year, a prominent sanitary authority remarked to me that no one of the speakers had defined a draught. I am going to attempt a definition ; you may take it for what it is worth. 1 will define itastheperceiitionof cold air in a vitiated atmosphere. I desire by the wording of the definition to indicate collaterally, first, that a draught ispartlyasubjectivephenomenon—one man's draught is another man’s fresh air—and, secondly, that in the o])en and fresh air, draughts properly so called do not exist. To avoid draughts, therefore, kecji the air fresh, and if you do not avoid all the evil consecpiences you will avoid some ; but do not arrange matters so that the atmosj)here fii*st becomes seriously vitiated and tlien i)artially r(*i)laced by cold currents. You would thru get a real draught. I am not a physiologist, and I do not understand these matters, but I imagine it possible that the human (wganism, in arranging things to contend with the poison of vitiated air, makes a certain disposition of its forces, and in arranging things to face tlie cold, ado])ts another dis})Osition; and further, that when you ask it to adopt both dis-](https://iiif.wellcomecollection.org/image/b22449474_0012.jp2/full/800%2C/0/default.jpg)
