136 



GASOMETERS. 



and likewise, the weight hearing a large proportion to the surface, unless somt 

 portion of it was removed by a counterbalance, the opposition to the flow oi 

 the gas into the vessel would be inconveniently great. 



Fig. 32. 



O) ( 



Figure 32 will explain the water-joint : a is the upper, and b the lower por- 

 tion of the gasometer, dipping into the water twelve inches ; c is a roller, 

 guiding the upper portion as it rises. These rollers may be placed about six 

 feet apart, entirely round the vessel. 

 D D are the standards, cast in several lengths, bolted to the tank, and bracer 1 



at the top by the girders E. 



F are the balance-weights, regulated according to circumstances ; that is tc 



say, if the gasometer, when brought into action, is found to oppose toe 



much resistance to the entrance of the gas, weights must be added, until 



the pressure corresponds with that of the other gasometers in the works 



or is equal to about three inches perpendicular head of water. It is ofter 



necessary to balance both the upper and lower vessels. 



The braces and ties for strengthening the sides and top of these gasometers 



are precisely similar in arrangement to those in ordinary use, and need not b< 



again described. A well for the reception of the outlet- and inlet-pipes is no' 



of course necessary, as the tank is above the level of the ground. The re 



ceivers and valves are the same. 



There is not the slightest drawback to the practical adoption of these Tele- 

 scope Gasometers ; they rise and fall with the same precision, and can be ad- 

 justed with the same nicety, as the single gasometer. The wear and tear is 

 about the same, and are repaired with the same ease, but their first cost is 



