The Construction of Boilers 



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of this class should not, however, be trusted 

 to alone as indicative of the condition of the 

 water in the boiler, but a special indicator 

 should be fitted to every boiler. A very 



F,g. 14. 



common one is shewn in fig. 14, where the rod 

 a a is connected with a float which rises or 

 falls with the varying level of the water in the 

 boiler. This is connected at its upper end 

 with a chain which passes over a wheel b, and 

 is supplied at its other extremity with a 

 counterpoise weight c. As the wheel moves 

 partially round, its index or finger point d 

 shews how the water level is in the boiler. 

 This apparatus, however simple, is not to be 

 relied upon at all times, as the rod is apt to 

 stick in the stufiing-box e. We know of no 

 form of water-indicator so efficient as that 



^^5tc^ 



known as Haley's, illustrated in fig. 15. The 

 copper float a is screwed upon a hollow spin- 

 dle b, and to which steam is supplied through 

 a hole at its [upper end, and from it to the 

 interior of the'float a, so that the pressure is 

 equal] within and [without. As soon as the 



VOL. I. 



water level falls, the float falls with it, and 

 the conical end c drops out of its seat, and 

 allows the steam to pass up the pipe </, and 

 acts upon a whistle placed in e. 



However efficient a form of feed-apparatus 

 may be, it is obvious that if not attended to 

 it might as well not be there ; rather, indeed, 

 it would be better absent, for then no trust 

 could be placed in it. Now, suppose that 

 the attendant screws down the handle of the 

 feed valve, closing it and admitting no water 

 to the pump, the pump might continue to 

 work well, yet no water be supplied to the 

 boiler. The reader may here say that surely 

 no man could be so stupid or blameworthy 

 as to do this : as stupid and as blameworthy 

 things as this are done every day, and being 

 done now may be done again. Let the 

 attendant, therefore, be sure that the hand- 

 feed valve is open. Further, let him be sure 

 that the rod a a, fig. 14, is not sticking in its 

 stuffing-box e, for if so the feed will not act. 

 Yet more, he must be positively certain 

 that the force-pump is passing water to the 

 feed-pipe : it may be working obviously 

 enough. This may arise from the "clacks" 

 or valves sticking in their seats, or the pump 

 not drawing. The best form of valve for a 

 pump is the " ball clack," which is not so apt 

 to stick as the conical valve. A good way 

 to start a sticking valve in a pump is to give 

 a few blows with a wooden mallet to the 

 case. To ensure a pump drawing water, it is 

 a good plan to have it provided with a " pet 

 cock." This is a small stop-cock added to 

 the pump and the pipe, by opening which 

 any steam that may have gained admission 

 to the body of the pump may be allowed to 

 escape ; or by means of which water may be 

 passed to the pump to enable it to draw, 

 should it have ceased to work. All these re- 

 marks shew the importance of attending to 

 all the appliances of a boiler. It is not 

 enough to know that one is working and the 

 other not — the whole of them must be work- 

 ing in conjunction. But we have not yet 

 exhausted the list of those appliances : hav- 

 ing, however, exceeded present space, we 

 must leave what we have further to give for 

 a future Note. 



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