LECTURES. 173 



measures practicable for securing the supply of air with the gentlest 

 movement, and tlirough a very large diffusing surface, which is more 

 and more agreeable in proportion as it approaches universal diffusion 

 from every perpendicular surface. The diffusion may, in some cases, 

 be given at the ceiling, under certain circumstances of breadth and 

 height, excepting such area as may be reserved therefor the discharge 

 of vitiated air. 



Leading facts were afterwards pointed out in reference to other 

 classes of buildings, in which his plans had been introduced, from 

 which the following selection is made : 



The Chapel Royal, at St. James's Palace, is ventilated by a metallic 

 shaft, worked by a series of gas lights, and the principal fire-places 

 discharge vitiated air into the same flue, with which they communi- 

 cate by copper tubes. There is an ascending movement of air in the 

 body of the chapel, but in the Queen's gallery the fresh air descends 

 from the ceiling and spreads horizontally over the seats. 



At the Pavilion, in Brighton, ventilation was effected by the intro- 

 duction of an iron shaft, heated by gas, and attached to one of the 

 turrets in the vicinity of the Minarets. 



At Buckingham Palace, in ventilating some of the state apartments, 

 a central shaft, having an area of twenty-seven feet, was formed where 

 only two feet of discharge had previously been provided, exclusive of 

 doors and windows. A back staircase, eight feet in diameter, was 

 appropriated for the discharge of vitiated air from the basement and 

 contiguous offices, which had previously flooded the state apartments. 



At the opera, in London, a discharge two feet in diameter was 

 replaced by another of seventy-five superficial feet area, but nothing 

 was done for the better supply of fresh air, except at the Queen's box. 

 The proprietors would not agree to give a proper supply. 



At the Old Bailey the whole of the arrangements were adapted to 

 the action of a large fanner, eighteen feet in diameter, which was worked 

 by a steam engine. 



In churches, the spire or tower was brought into action as a venti- 

 lating power, whenever permission was given for this purpose; and 

 when the church was surrounded by a grave-yard or other source of 

 vitiated air it was recommended that the spire should be so divided 

 within that one part might supply fresh air from a considerable alti- 

 tude above the level of the ground, the other portions being used for 

 the discharge of vitiated air at a higher level. 



In prisons. Dr. Reid had used the ventilating shaft principally, and 

 preferred an ascending movement in the individual cells, allowing 

 the prisoner the control of the window to a limited extent. 



In barracks for soldiers great suffering was often experienced from 

 defective ventilation, and the men often became practically familiar 

 with this question from the extent to which their arms and accoutre- 

 ments rusted in some places compared with others, entailing on them 

 a degree of labor, in preparing for parade, of which they made more 

 complaints than of its influence on their health. 



In schools, he preferred the action of a single ventilating shaft suf- 

 ficient to control the ventilation of every apartment in the building, 

 and urged also the general adoption of one regulating discharge from 



