Report of discussion on Mr. Shaw's paper, "Ventilation as a dymanical problem", delivered at an ordinary meeting of the Society, on February 6th, 1902, at the Medical Rooms, Chandos Street, W.

Date:
1902
Catalogue details

Licence: In copyright

Credit: Report of discussion on Mr. Shaw's paper, "Ventilation as a dymanical problem", delivered at an ordinary meeting of the Society, on February 6th, 1902, at the Medical Rooms, Chandos Street, W. Source: Wellcome Collection.

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    reasons based upon the electrical analogy which he would not stop to explain. Dr. Lyon had suggested that the electrical analogy was not appro¬ priate. He thought Dr. Lyon had in mind more particularly the currents of air in the ventilated space. The analogy was more specially applicable when a number of connected rooms was under consideration. The other day he had been called upon to advise upon plans for the ventilation of the out-patient department of a very large hospital. There were, perhaps, some 300 rooms on three floors, with windows, air gratings, doors, passages, corridors, staircases and lifts. It was a difficult problem, and the probable mode of working of the system was unintelligible to him until the possible circuits of air currents had been marked down in order that some sort of picture could be formed of them ; no doubt it was an extremely complicated one, but it was a picture from which one could get a definite idea of the way things would act, even in a complicated plan. The analysis of the ventilation of an elaborate building was a most complicated problem, and he did not believe its solution was possible with any degree of accuracy or satisfaction, unless some sort of picture was obtained more simple than the architect’s plans with all the architectural de¬ tails. It was for that reason that he had used the electrical analogy for the purpose of describing something which otherwise it was almost impossible to describe. Mrs. White Wallis had demurred to his definition of a draught, but he did not mind that in the least, for he did not attach any final importance to his definition. What he wanted to point out was that in his experience cold air could injure him in two or three ways, and so produce different kinds of disease. He thought there ought to be some practical definition for practical ventilators, some distinction between currents of air that were associated with poisonous conditions and currents of fresh air that simply reduced temperature, such as are felt in the open air. It was for that reason that he had limited the definition of a draught to the perception of cold air in an unventilated or badly ventilated space. Probably the physiological effects under the circumstances differed. There was another effect of cold air in an enclosed space, to which he had not referred ; that is to say, one part of the body might be kept persistently cold, while another part would be warm. He did not know how the human body accommo¬ dated itself to this state of things, but, at the same time, he thought there was a marked distinction between the effect of a draught in an ill-ventilated space and the effect produced by an air current out of doors. Whether to the latter the term draught ought to be applied he could not undertake to say. Mrs. Wallis also asked a question with regard to the ventilation of classrooms occupied by fifteen people when there was no means of warming the entering air. He was afraid that was a very difficult thing ; in fact, to accomplish that was next door to the impossible. A classroom for fifteen persons should be provided with some 40,000 cubic feet of air per hour ; to maintain the requisite supply of air, the up draught of three ordinary chimneys would be required. He knew no means of introducing 40,000 cubic feet of cold air into a room of moderate size and disposing of it in such a way that the room would be comfortable for those persons who were liable