The Mechanical Handling and Storing of Material

THE HANDLING OF MATERIAL BY PNEUMATIC MEANS 211 pipes, and the air became laden with dust and fine siliceous matter to such an extent as to render it impossible for men to whilst the elevator was at work. 1 his latter objection was not sus- pected by the patentees until a plant had been shipped and set to work on the Danube, when this proved an absolutely fatal objec- tion to the use of the machine. Duckham’s System.— The first modern suction eleva- tor was erected by the Millwall Dock Co., under the Duckham Patents,1 the first of which was taken out in the year 1890, and it is under these patents that all the existing pneumatic elevators at present in use in the United Kingdom were constructed. As the principle has already been •outlined, it will now suffice to give the details of the different working parts of the invention. One of the chief items is the air' trap through which the grain finds its exit from the tank with- out destroying the vacuum. This is effected by an ingenious ar- rangement illustrated, together with the tank, in Fig. 283. 1 he pipes a and c are con- nected to the tank b, the former leading to the grain store or to the ship to be unloaded, and the latter to the exhauster. Beneath the tank b is the apparatus which withdraws the grain from the tank automatically without de- stroying the partial vacuum in the same. The apparatus con- sists of a receptacle divided into two compartments h and h1, which oscillates on its axis L, so that alternately h and h1 will receive, the grain through the remain in the ship’s hold for the purpose of trimming Fig. 283. Duckham’s System of Pneumatic Elevating. aperture d. Ihe delivery spouts k and K1 open and close with the same oscillating Duckham’s Pneuæatic elevator and conveyor are described in Engineering, 29th January 1897, th July 1893; also in The Engineer, 19th February 1897 and 8th April 1898. See Proceedings Inst. C.E., vol. cxxv.; see also Proceedings Inst. Naval Architects, 31st March 1898.