MECHANICS AND USEFUL ARTS. 19 



be another pumping "station, to lift the water to the reservoir. The 

 southern reservoir is only five acres in extent ; that on the north is 

 fourteen. In the reservoir it will be deodorized and discharged in a 

 similar Avay to that we have already described. 



" The pumping stations will each consist of an engine-house, contain- 

 ing ten boilers calculated to work up to five hundred horse-power nom- 

 inal. This power, working through eight pumps of seven feet diameter 

 and four feet stroke, will "daily raise 119,000,000 cubic feet of sewage 

 from nineteen feet below low water to the level of the outfall ; but, in 

 case of necessity, the pumps can raise 250,000,000 cubic feet per day. 

 The reservoir into which it will all flow is not yet finished, but when 

 roofed in with brick will hold 20,000,000 gallons of sewage. 



" The total length of the three rows of intercepting sewers, the course 

 of which we have sketched on each side of the river, will be fifty 

 miles, and before all the works are completed 800,000 cubic yards of 

 concrete will be consumed, upwards of 300,000,000 of bricks, and 

 4,000,000 cubic yards of earthwork." 



During the past year, a part of this great work has been so far com- 

 pleted, that a portion of the sewage of London has been diverted from 

 its old channels. 



UNSHAKABLE TIMBER SHIPS. 



At the last meeting of the British Association, Admiral Belcher stat- 

 ed that many years since, Mr. Walters, an architect, tried to render 

 ships for mercantile purposes unsinkable, by introducing copper cylin- 

 ders between the timbers, the hold-beams, and, indeed, every opening 

 where the cargo did not prevent ; and he calculated that these dis- 

 placements or cells would about compensate for difference of specific 

 gravity between cargo, vessel, and gear, so as to simply reduce her to 

 the state of a water-logged craft, to save crew, vessel, and such portions 

 of cargo as might be secured in air-tight vessels. 



Latterly, the pneumatic trough had suggested itself to his (Admiral 

 Belcher's) mind the propriety of close-ceiling the holds, or under- 

 planking the hold-beams, and saving those spaces between them for 

 the storage of light dry-goods above that deck (which was generally 

 lost), ancf placing loose planks (indeed, as we were in the habit of 

 hatching many, of our brigs of 386 tons and under) as a temporary 

 deck. Now, in the event of a dangerous leak, or even a large hole being 

 stove in the bows or bottom of a ship, he proposed securing the hatches 

 from beneath to hatches above, screwed firmly in opposition to each 

 other, and filled in by pitch from the upper or open hatch. Now, it 

 would be apparent that if the ship was air-tight, the water could only 

 enter so long as the air was compressible, and by inverting the pump- 

 boxes and rendering them air-pumps, the leak would not only be 

 stopped, but, by the continued action of the air, it would be expelled by 

 the very orifice by which it entered. Therefore, the customary and con- 

 tinued labor and wear of the powers of the crew would not be required 

 to such an extent, if at all, when once the necessary quantity of air 

 had been forced in. He came now to the use of iron plates in forming 

 air-tight cellular vessels, and he hoped to 'be able to show that, by 

 pursuing this mode of construction, a vessel would not only be very 

 much less liable to injury by collision with a ram, but if carefully and 



