38 CONSTRUCTION AM) MANAGEMENT OF SMALL GASWORKS. 



small works. Whatever the form of furnace used, the 

 working results cannot be expected to equal those that 

 should be obtained when working continuously, week in and 

 week out, under skilled supervision, and with such refine- 

 ments as analyses of flue gases. In the large works, any 

 one bed is lit up, and worked continuously until so far worn 

 that shutting down for repairs is necessary. But in the 

 small works there must be changes every few months, in the 

 way of letting down or taking up, and, for some period of 

 the year, banking up at night. The yield per ton must 

 necessarily be somewhat less, and the fuel account be 

 greater. 



The special difficulty in small works is to prevent or 

 minimize idle time on the retorts, because idle retorts 

 under fire are white elephants, in more senses than one. 

 Not only do they require more fuel, but they wear more 

 rapidly, and are more liable to develop cracks and leaks 

 under irregular work. And this leads up to the con- 

 sideration of retort house units. By this expression I 

 refer to the number of retorts in a bed, because half a 

 bed cannot be under fire at one time. It must be the 

 whole or none. And a retort cannot be worked with satis- 

 factory results on less than a full charge. In large works, 

 the retort unit may be as large as working arrangements 

 will admit, and there is no need to limit the number of 

 retorts in a setting. But in the small works it is possible to 

 have both the retort and the furnace units too large or too 

 small, having regard to the maximum and the minimum out- 

 put, and to the variations in demand throughout the year. 

 There is too much adherence to the 9-feet by 1 6-inch 

 section retort, a very good size for a 30,000,000 cubic feet 

 works, but not necessarily the best for a 3,000,000 works. In 

 a works where the daily demand ranges from 5,000 to 15,000 



