TRANSACTIONS OF THE SECTIONS, 213 
the smaller or ball valve sits upon the centre of the larger one. The larger valve is 
weighted by means of a lever and ball, as in the common safety-valve ; there is an 
iron bridge or cover casting, which fits to the large valve and forms the centre for the 
centre pin to give pressure upon the valve enclosed: and resting upon the centre of 
the large valve is the ball valve, which is weighted bya dead- weight inside the boiler, 
the dead weight being comprised of iron plate castings. When the steam exceeds the 
pressure this ball-valve is weighted to, it escapes through the openings in the bridge 
casting into the dome or shell and out into the atmosphere. As soon as the ball-valve 
lifts from its seat, the large one also lifts from its seat ; and thus a double discharge is 
given to the excessive steam. The feature here presented is of importance, inasmuch 
as we find a valve possessing an opening or discharging area equal to an ordinary 
safety-valve 81 inches diameter. The valve cannot be weighted beyond its working 
pressure whilst the boiler is at work, as it will be seen; should an attempt be made 
to weight the lever or even press upon it with all force, that would be useless so long 
as the ball-valve was there ; and even should the ball-valve be weighted intentionally 
whilst the boiler is standing for cleaning, &c., it may instantly be detected by placing 
the ball on the lever in its ordinary working place; and by getting up the steam you 
will discover such tamperings and to what extent, by the marks on the lever. Yet 
when the boiler is at work it defies any tamperings. 
With respect to its improved arrangement for deficiency of water,—there is 
a lever suspended in the boiler; the rod which bears the weight for the ball- 
valve passes through a large hole in’ the centre of this lever. On this rod is fixed 
a collar, which is arranged so as to allow the Ings of the lever to come in contact 
with it as before mentioned. There is a lever or beam suspended in the boiler, one 
end of which bears a large float, the opposite end a balance weight, to counteract the 
buoyancy of the float when immersed in the water, and to keep the lip of the lever 
up against the under side of the top of the boiler ; the float is immersed in the water 
to such a depth as is called low water mark. When the water begins to leave the 
float, the specific gravity of the float is then brought upon the end of the lever, which 
turns upon a centre; the lugs then are brought into contact with the collar on the 
rod, and the valve is raised from its seat. 
Should the water still get lower, the valve continues to rise, and will do so until 
the water be again at its proper height : should the warning be disregarded, the steam 
will all be discharged from the boiler and stop all working, and render explosion 
impossible. 
On the Drainage of the Metropolis. By E. Jones. 
The author proposes to place portable tanks within cesspools constructed in the 
sewers, each capable of holding about one ton weight of solid sewage matter. A 
bar or grating to be fixed within the sewer, at one side of the tank, so constructed as 
to act as a coarse filter to check the solids which will then be precipitated into the 
tanks. The tanks when full to be lifted out by a portable crane, a lid being first 
securely fixed thereon, so as to prevent the escape of the least smell. Previous to the 
act of removal the communication with the sewers will be cut off, by doors or flood- 
gates, made to slide in a grooved frame, by which the water in the sewer will be 
arrested and the effluvia prevented from escaping into the streets during the removal. 
The author suggests that a series of these tanks be placed at a quarter of a mile 
distant from each other within the sewers, and that thus the drains could beeffec- 
tually scoured. He estimates that the cost would not exceed one and a half million : 
also, that the Thames should be embanked; within which embankment it is pro- 
posed to construct, at the end of each main sewer, three reservoirs, to be divided into 
compartments and fitted with moveable tanks to collect the sediment produced by 
deodorizing with lime. Ornamental chimney shafts with furnaces to be constructed 
near the mouths of the main sewers for the purpose of drawing off the noxious gases, 
_ and also for the purpose of consuming refuse vegetable matter. The resulting ashes 
may be used for deodorizing the sewage. 
On the Application of Mechanical Power to the Bellows of Organs. 
By D. Joy. 
To work the feeders of an organ, a reciprocating motion alone is required ; but it 
