The manhole affords ingress into the boiler for inspecting and for scaling or cleaning it, the nozzles being for a safety valve. At e is a hand-hole for washing out and cleaning the boiler. p is a damper in the fire door for admitting air above the fire bars, and r is a damper for regulating the draught.
In the brick walls that support the boiler there are air spaces to prevent the conduction of the heat through and prevent cracking of the brickwork. The tubes are arranged in vertical and horizontal rows and are equally spaced throughout.
Fig. 3274.
Fig. 3275.
[Fig. 3274] represents the front end, and [Fig. 3275] a longitudinal sectional view of the front end of a boiler of this class. In this case, however, the pipes for the water gauge pass direct into the boiler.