154 LECTURES. 



in looking to this question as one that had to regulate practice in 

 construction and the appliances used in connexion with ventilation, 

 he was satisfied that ten cubic feet per minute for each person would 

 be amply sufficient, wherever it was possible to control the tem})era- 

 ture and the hygrometric condition of the air to be used. 



The practice of merely determining the amount of cubic or super- 

 ficial space to be given for each soldier in a barrack, each patient in a 

 hosi)ital, or every criminal in a ])ris()n, and leaving every other question 

 or means of ventilation to accident, had never been satisfactory, and 

 was now abandoned in all the best buildings for these and other 

 purposes. No dependence whatever can be placed on such a provision 

 beyond the actual amount of pure air they may contain before occu- 

 pation. The true question is, to determine the amount of pure air 

 that can be made to pass through wards, cells, or any other spaces in 

 a given time, with a maximum of the ventilating power in action, 

 valves or other arrangements reducing the elfect to any desirable 

 standard. 



In cases with systematic ventilation properly applied, a man in a 

 room densely crowded may have more air than one in a confined 

 area with ten times as much space for his own occu[)atioa. Rooms 

 in different habitations vary as, much in the amount required at dif- 

 ferent times and seasons as many public buildings. Further, there is 

 nothing more deceptive to those who have not studied the subject 

 practically tlian the numbers of persons that can stand on a given 

 space. In special trials, made with the view of determining the 

 numbers that can be accommodated on a floor of known size, several 

 cells were selected at the prisons at Perth, in Scotland, and able- 

 bodied men (engaged at that time in completing the building of the 

 works) were requested to stand in them as close as they conveniently 

 could. Seventy were then counted in one cell having a floor of 

 seventy-two feet, and ninety in another having a floor of ninety-two 

 feet. Pie had repeatedly seen at the bar of the House of Peers, 

 in London, knd in many other places an individual standing upon 

 each area of one foot. When the body of the late Duke of Wel- 

 lington lay in state at Chelsea hospital, previous to the funeral, he 

 had seen a more dense crowd than he had ever witnessed on any pre- 

 vious occasion. Many were literally crushed to death in this crowd, 

 and numbers who escaped death had the appearance of persons who 

 had i'allen into a stream of water and been thoroughly drenclied. 

 The morning was cold, calm, and gloomy, such as would have suited 

 the description many foreigners give of a London atmosphere at that 

 period. There was no fog, however, though a small cloud of vapor 

 hung heavily over the densest part of the crowd. It should be re- 

 membered, then, that in cases of great interest, all rooms, public and 

 private, are liable, generally or locally, to have like numbers crowded 

 into them, and it becomes, therefore, imperative on those who desire 

 ventilation to state the number to be provided for, rather than the 

 mere area of the floor. 



In the chambers for Congress the floor space allotted for individual 

 members was upwards of twice as much as that given at the Houses 

 of Parliament in London, taking into consideration that occupied by 



