LECTURES. 167 



atnlcably and accurately carried out, then an inipermm in hnperio will 

 interfere at every step. If the architect have supreme power, then 

 he must necessarily become responsible for the ventilation, particu- 

 larly if he controls and determines the apertures for ingress and 

 egress, and the amount of diffusion given to the entering air. The 

 ventilator cannot be responsible for his plans if lie disapproves of 

 alterations which the architect may carry into effect. Again, if 

 the ventilator shall have the directing authority, the architect may 

 say that he will not be responsible for the appearance of decorations 

 and their general effect if they are adapted for ventilation in a 

 manner of which he does not approve. It will be obvious, then, that 

 until schools or colleges of architecture shall give the future student 

 the opportunity of applying himself to this subject as much as its 

 importance demands, we must consider this branch in a state of transi- 

 tion. When the architect does not profess to attend to ventilation, it 

 cannot receive from him that full assistance and development which 

 could otherwise be given in the original design, and in harmonizing all 

 the conflicting claims of the different departments of the profession. 

 Dr. Reid then gave experimental illustrations of the action of ven- 

 tilating shafts worked by heat, of steam ejected from a small glass 

 boiler, and of different classes of instruments for the movement of 

 air, pointing out more particularly the difference between the air- 

 pump, the screw, and the fanner. In speaking of instruments alone, 

 he gave a decided preference to the two latter, from the simplicity, 

 continuity, and equality of their action ; though, in particular cases, 

 where air at a higher pressure than usual was necessary, he preferred 

 the air-pump. 



At the same time, wherever a ventilating power was essential, and 

 the difficulties to contend with were not great, he recommended the 

 shaft as abundantly sufficient for all ordinary purposes ; stating that 

 any common laborer could be taught to attend to it, and that it merely 

 required to have a proper supply of fuel from time to time ; whereas, 

 with an instrument worked with an engine the constant attendance 

 of an engineer was essential. That was the result of his experience. 

 He had been the first, so far as he was aware, to introduce large fan- 

 ners, worked by steam engines, fitted up expressly for ventilating 

 buildings, and still recommended their use as much as before, under 

 similar circumstances ; but he could point out places where they were 

 not necessary, and where the substitution of a shaft would effect a 

 considerable annual saving. 



In respect to the course which the air should take in passing 

 through any apartment to be ventilated, much should depend on the 

 special difficulties to be overcome in each individual case. The ascend- 

 ing movement was preferred for all ordinary purposes. He had used 

 that movement more extensively in public buildings than any other, 

 though in old buildings, where it had to be applied under great limi- 

 tations, there were often many difficulties to be met. ^ Among these 

 tlie most formidable in general was the want of sufficient diffusion 

 .for the entering air. In the late House of Commons, which was made 

 the basis of experiment for determining the accuracy of his views and 

 tlie test of their application to the new houses of Parliament, he had 



