The Hospital Requirements of Sydney. 33 



degree proved itself equal to the natural ventilation caused by 

 opposite windows judiciously placed and proportioned. 



In the old countries of Europe it has been necessary to find 

 some plan for replacing this natural supply during the frequent 

 inclement seasons, by one in which the air entering the wards 

 could be warmed ; and the great difficulty experienced in thus 

 obtaining a sufficient supply of pure air to meet the demands of 

 hospital wards, has led to the cry which has latterly been heard 

 far and near for an increasing cubic space ; but I venture to ex- 

 press an opinion, that the steed of science has in this instance 

 been allowed to carry his rider somewhat further than it was 

 judicious to go. No doubt, the principle of the cubic space theory 

 is true, especially when applied to wards occupied temporarily, 

 but it is inapplicable beyond a certain point to those constantly 

 tenanted by a definite number of patients. 



The difference between space and ventilation hinges on an in- 

 teresting point of science, which has been so well laid down by 

 Professor Donkin, F.R.S., that I cannot refrain from giving a brief 

 explanation of it. " It is now generally acknowledged that the pro- 

 ducts of respiration, like other gases, obey rigidly the law of diffu- 

 sion, and that even a single cubic foot of air exhaled from the 

 lungs almost immediately spreads itself through the atmosphere 

 of a room, and is, in fact, diluted in the surrounding air. Sup- 

 posing, then, a man occupying a room of definite size, it is evident 

 that unless as much fresh air is admitted into the room during 

 each respiration as that polluted by the lungs during the same 

 period, the atmosphere of the room must continue to be more and 

 more saturated with poisonous products. If the room be a large 

 one the time taken to saturate its atmosphere will be greater than 

 if it is a small one, and if its size be vast, and it is occupied but 

 for a certain period, it will be necessary to introduce per hour a 

 less amount of air than would otherwise be requisite." Under 

 the circumstances, therefore, of intermittent occupation, cubic 

 space is an important element. The large room has not become 

 poisonous at the time its tenant leaves it, and before it is again 

 required for occupation, diffusion has purified its atmosphere for 

 the next inhaibtants. The degree of purity of a room will ulti- 

 mately depend in no way on the size of the room, but solely on 

 these two things — 1st, the rate at which the emanations are pro- 

 duced ; 2nd, the rate at which the fresh air is admitted. 



It cannot be denied, as a principle, that in wards constantly 

 occupied space alone has little to do with purity of atmosphere. 

 The difficulties and large expenditure which attend every attempt 

 to ventilate hospitals in England, fortunately, do not to the same 

 extent hamper our endeavours in Sydney, and I shall now pro- 

 ceed to explain the system which appears to me calculated to 

 offer the most satisfactory result, 



