620 GAS-WORKS 



of the exposure of tho roof to storms of groat violence, and to rapid corrosion from tho 

 proximity of the sea, it was considered desirable that it should be of groat strength, 

 and that its parts should bo few and accessible. Accordingly the roof was designed to 

 sustain a weight equal to 60 Ibs. per square foot of external surface, or72 Ibs. per squaro 

 foot of plain covered. With that weight no piece of metal was subjected to a tra>ilo 

 strain exceeding five tons per square inch of section, and tho strains on tho parts in 

 compression varied from two tons to four tons per square inch of section. The roof 

 consisted of ten Warron trusses of 84 foot span and 14 feet deep, placed about 30 feet 

 apart. Across tho top beams wore laid four lines of latticed purlins, and upon these 

 purlins rested the bars carrying the skin of the upper portion of tho roof. Tho lower 

 portion of the roof was formed with tho framed struts of trusses, and some lighter 

 intermediate framed struts were joined to tho bars immediately over them. Tli.-uot 

 on the walls was prevented by a series of ties, with screwed couplings, placed between 

 the foet of tho intermediate rafters and principal trusses. The laths wore of channel- 

 shaped section, and Duchess slates wore fastened thereto with screwed clips, two to 

 each slate. Four wrought-iron rudimentary shafts, 10 feet in diameter, enclosing the 

 tops of the chimneys, allowed the smoke to escape ; there tfas also a protected opening, 

 5^ feet wide, along the ridge for its entire length, for the same purpose. The roof 

 was constructed by Messrs. Newton and Chambers, of the Thorncliffe Ironworks, and 

 its cost, ready for slating, was SI. 16s. per square of 100 feet. There was twenty-four 

 benches of these retorts. Each bench had eight long retorts, and there being two 

 mouthpieces to a retort, made 384 mouthpieces in all. The retorts were cylinders 

 16 inches in diameter and 20 feet long ; and each would carbonise one ton of coal per 

 day. Allowing one-sixth the number for reserve, the remainder would produce 

 1,500,000 cubic feet of gas every twenty -four hours, or 300 millions per annum. The 

 ascension pipes were 6 inches diameter at the bottom, and 5 inches at the top. Tho 

 hydraulic mains, two to each block of six benches, were of larger section than usual, 

 and were fastened with separate outlets to the collecting main. The buckstaves were 

 of rolled iron, with tie-rods fixed clear of the brickwork. The gas, as it was pro- 

 duced, passed with the tar and liquor from the collecting pipes of the hydraulic mains, 

 at either end of the retort-house, into 12-inch mains carried along the inside, and 

 uniting in the middle of the south wall of the retort-house, from which point they 

 issued by a 16-inch main to the condensers. At the end of the horizontal condensers 

 the tar and liquor were deposited in a tank, whence they were led to the tar-tanks 

 under the coal stores. From this point the gas passed successively through the ver- 

 tical condensers, exhausters, scrubbers, purifiers, station meters, and driving exhausters, 

 in the main leading to the gasholders at Hove. The mains and connections were 

 16 inches in diameter throughout. 



The engine-house contained four exhausters, each exhauster being driven directly 

 by an independent engine. Two of these exhausters were for the purpose of removing 

 the gas from the hydraulic mains and driving it through the scrubbers and purifiers. 

 A self-acting by-pass was carried from the inlet of the exhausters to the inlet of the 

 purifiers, and each exhauster was connected with a governor, which also acted as a by- 

 pass. Only one of these exhausters was in use at a time, tho other being in reserve. 

 The remaining exhausters were also used one at a time, and were for the solo duty of 

 receiving the gas at the outlet of the station meter, and of delivering it into tho mains 

 leading to the gasholders at Hove, so that the works were relieved from all pressure 

 from the weight of gasholders and resistance of tho intervening mains. An hydraulic 

 by-pass made to resist back pressure was placed between the meter and the main, 

 and each exhauster being connected with a governor, a slight uniform pressure was 

 maintained at the outlet of the meter. 



' The scrubbers used at these works wore the first of the kind erected. They con- 

 sisted of a series of perforated discs or screens, which revolved slowly in a tank half 

 filled with liquor, so that the gas might pass through tho portions of tho screens above 

 water. Tho gas was in this way divided into a series of small streams, each stream 

 being brought equally into repeated contact with a thoroughly wetted surface. The 

 screens being fitted at tho edge with an elastic fringe, made by preference of bass, 

 there was but little friction against the circular portion of the tank, and as no ad- 

 vantage was gained by a speed of more than fifty revolutions per hour, the power to 

 keep tho screens in motion was very small. There was a slight difference in tho 

 heights of the bases of tho scrubbers, tho first being tho lowest and the third tho highest . 

 In working, tho gas passed through each scrubber from tho lowest to the highest of 

 tho set. Water entered the highest scrubber and ran through the middle and lower 

 scrubbers to the liquor tanks, tho desired strength of the liquor being obtained by 

 regulating tho volume of water admitted to tho highest scrubber. Tho scrubbora re- 

 moved 95 per cent, of tho ammonia, 50 per cent, of tho sulphuretted hydrogen, and 

 from 30 per cent, to 50 per cent, of tho carbonic acid existing in tho crude gas. They 



