Doolitile's Hydrostat. 65 



the convex side downwards ; its specific gravity should be 

 such that not more than one half or two thirds of its volume 

 shall be immersed. 



At any convenient place on the feed or supply pipe, between 

 the forcing pump and the boiler, let there be adapted a vertical 

 waste-pipe, at the top of which there might be a valve loaded 

 with a weight greater, per square inch, than the expansive force 

 of the steam intended to be used, so that, whenever the stop- 

 cock shall be opened, the waste valve shall be closed and the 

 water forced into the boiler, and when the cock is closed, the 

 waste valve shall open at each successive stroke of the for- 

 cing pump, and allow the surplus water to escape into a pipe 

 arranged for the purpose of conveying it away from the en- 

 gine ; it will readily be seen that the supply pump must al- 

 ways be kept working when the engine goes, and must force 

 a quantity of water somewhat greater than is required to sup- 

 ply the boiler. 



If the above apparatus is to be applied on board steam- 

 boats, where it is feared the agitation of the water in the 

 boiler, caused by the motion of the boat, should derange the 

 operation of the floater, let the floater be surrounded by a 

 sort of cistern which shall be secured to the bottom and ex- 

 tend to near the top of the boiler, which cistern shall have a 

 small opening near the bottom and be entirely open at the top, 

 the pressure of the steam within and without the cistern being 

 equal, the general level would be maintained within, while 

 the smallness of the lower aperture would prevent any sud- 

 den influx or eflux of water from raising or lowering the floater 

 more than that general level would require. The stem of the 

 floater should be continued through the lower or convex side, 

 and traverse a guide so placed as to answer the double pur- 

 pose of keeping the stem in its proper place, and of preventing 

 the floater from sinking lower than to open the entire aperture 

 of the cock, the top of the stem may also pass through a guide 

 to preserve its position, or the verticality of the stem may be 

 maintained by any other of the methods now used for preserv- 

 ing parallel motion. 



Instead of the ratchet and pinion, a chain and counter 

 weight may be used, or the stem of the floater, may be at- 

 tached to a crank on the axis of the stop-cock, though I 

 think the former method preferable. 



I do not claim, as new, any single or detached part of the 

 above apparatus ; but I do claim as new the combination and 



Vol. XIII.— No. 1. 9 



