354 Scientific Proceedings, Royal Dublin Society. 



on an average from the three together, about 1060 cubic feet per 

 minute, or 63,000 cubic feet per hour. 



The measurements of the air-currents were made with an anemo- 

 meter of Cassella's construction, which had been properly tested 

 and corrected for measurements at different speeds, and where 

 necessary the corrections were applied to the readings on the dial 

 of the instrument. Fixed to the end of a wooden rod, the anemo- 

 meter was held in position at the top and bottom, at each side, 

 and also within the centre of the opening of the flue. The mean 

 of the five measurements in these positions was taken in each case, 

 and they were each repeated and verified. The height of the 

 barometer, the temperature inside and outside the building, 

 whether the air was calm or the wind strong, and also the direc- 

 tion of the wind, were noted. Lastly, the daily consumption of 

 gas was recorded, and the number of hours during which it was 

 burning in the flues. The observations were continued daily on 

 two of the three flues during a period of six months. On several 

 occasions no gas was burnt, the draught being strong enough 

 without. This was caused by the velocity of the wind blowing 

 across the mouths of the chimneys. Eventually it was thought 

 desirable to note the direction and force of the wind; and this was 

 done daily during a period of two months. 



As the details are valuable for reference, I submit a tabulated 

 statement of them to the Society ; they are of general application, 

 and clearly show what amount of ventilation may be expected and 

 should be obtained under almost any atmospheric conditions. 



I have always regarded it as important in the construction of 

 laboratories that the fume-chamber space should be large and 

 evenly distributed, so that the general ventilation of the laboratory 

 should, to a large extent, be effected through these chambers. 

 This means, of course, that there should be an adequate supply of 

 fresh air evenly distributed so as not to create draughts. Unless 

 there is such a supply, the same chambers will not act with full 

 efficiency. To indicate the amount of ventilation effected through 

 the fume- chambers, the general result of some measurements is 

 here recorded. It should be mentioned that the only entrance to 

 the laboratory was by a door leading on to a wide staircase, on 

 the landing of which was a large window. When the laboratory 

 windows were not open, the chief supply of air came through this 



