I 

 44 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS. 



of ventilation openings. Too much draught is as bad for 

 the workmen as not enough, and will interfere with the 

 economical and effective heating of the retorts, and means 

 a considerable addition to the fuel bill in the course of a 

 twelvemonth. In a house where the number of retorts 

 open at one time does not exceed three, there is no reason 

 for making provision to take away the products from twenty 

 or thirty. A ridge ventilator extending from end to end, and 

 a large aperture in each gable wall, may not be out of place 

 in a house containing some hundreds of retorts, and with 

 drawing or charging every hour, but where only one man 

 works at a time, it is too much. The efficiency of the 

 ventilation is not in proportion to the area of the apertures, 

 and I have seen so-called ventilating arrangements that were 

 more effective in beating the smoke about the ears of the 

 workman than in removing it. A few short vertical shafts 

 are more effective than louvres or other obstructed outlets, 

 and they should be a narrow rectangle rather than square 

 in section, so as to spread the smoke into a thin layer. 

 There is a great difference in the appearance, as viewed 

 from outside, of smoke issuing from an aperture 18 inches 

 square, as compared with one 9 inches by 3 feet in hori- 

 zontal section. The outlets for the smoke and hot air must 

 be proportional to the inlets, but the latter part is apt to be 

 entirely overlooked, and it seems to be supposed that the 

 outlets are all that is required. The hot and foul air will 

 not be drawn away unless there is a proper inlet for fresh 

 air to take its place. A large extent of outlet area, with 

 no inlet other than that incidentally afforded by the 

 door, means an uncomfortable, draughty, and probably 

 badly ventilated house. It is easy to see if a house clear 

 freely ; and if it does not, the condition can frequently be 

 improved by very simple means. 



