414 



Mr Shaw, On an experiment in Ventilation. [May 10, 



To secure the advantages of the second method I have laid 

 an open tube 24" x 12", one opening of which is horizontal and is on 

 the level of the rail of the partition between the lecturer and 

 the audience and just behind that partition, the other opening 

 is in the boiler room where are the two furnaces of the hot-water 

 apparatus of that part of the building. By closing the door of 

 that room and measuring the amount of air which went through 

 the window to supply the fires I had calculated that I could 

 by means of this tube extract 18,000 cubic feet of air per hour 

 from a part of the lecture-room where the air was certainly 

 impure. I had intended to increase the hot air inlets by adding a 

 Tobin between two windows on the south side connected with 

 one part of the case of the hot-water pipes, providing the opening 

 to the outside air in another part of the same case, but this has 

 not yet been done. 



The present arrangement of exhaust and supply Tobins may 

 therefore now be represented by Fig. 2. 



Fip. 2. 



Tand T'are the old Tobins, Fthe new position of the ventilator 

 in the east wall. V the ventilator in the west wall as before. 

 W the new tube connected with the furnace room. 



I have made some measurements of the amount of air which 

 passes through the various openings, first with the new shaft open 

 and secondly when it is closed. The results are given in the 

 following table. The cubical content of the room is about 36000 

 cubic feet. 



The measurements were taken by means of a Casella wind- 

 gauge. They are of course very rough and especially so in the 

 case of the inlets, the rate for which varied very considerably with 

 the wind. It will be seen that the new shaft does very much what 



