The Supply Department.
Page 17
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Selected Information which is likely to be of Isterest to Makers, Owners, and their Buyers.
Reserve Cells for High-tension Ignition.
A new " dry " battery, known as the " Dura " cell, has recently been introduced by Siemens Brothers and Company, Limited, of 12, Queen Anne's Gate, Westminster, S.W. The special feature of these cells lies in the fact that, as delivered from the factory, the exciting agent is in an absolutely dry and inert condition. No chemical action can take place within the cell, nor can any current be drawn from it until plain water has been introduced through a corked tube, which is provided for that purpose. After a certain amount of water has been added, a short time must be allowed for it to become absorbed by the exciting agent, after which the cell should be again filled with water and the cork replaced; the cell is then ready for working.
Duplex Air Tubes for Pneumatic Tires.
It is probably correct to assume that the component of a motor vehicle which offers the largest field for improvement, particularly with regard to reliability and to mileage cost, is the pneumatic tire. The claims for spring-wheel devices and elastic-tire improvements, lodged at the Patent Office during the past twelve months, considerably outnumber those advanced for any other single class of invention. It is evident, therefore, that the need for and the possibility of considerable improvement is generally realised. An arrangement which possesses considerable interest in this connection is that known as the MarshallDuplex air tube. Reference to the drawings which we reproduce will indicate the simplicity of the idea which has been embodied. Ti and T2 are the twin or duplex inner tubes. These are solutioned together along a i-inch centreline. It will be noticed that, unlike several similar devices that have already been employed, both the tubes are easily accessible for repair. Any ordinary non-return valve (C) of standard pattern may be employed for the inner of these two tubes. Directly above this valve the two tubes are in communication with each other by means
of a special metal plug (I)). This plug has, stretched over its centre hole, a rubber membrane which acts as a non-return valve for the outer of the two tubes. The nut which secures this secondary valve is normally made to fit tightly into the top of the ordinary valve piece (V). Under normal conditions the secondary valve (P) will be seated in the socket (V) and air will pass up into the outer of the two tubes. In case of puncture of this first tube it is only necessary to dislodge the plug (P) by
means of a special stem (D) which is provided on the dust cap. The second tube may then be inflated. The pressure of the air in this second tube forces the plug and its auxiliary rubber valve up against the outer cover in such a manner that no air can escape from the inner of these two tubes. The Duplex Motor and Cycle Valve and Tube Syndicate, Limited, is the somewhat unwieldy name of the manufacturer, and the offices are at Clarence Chambers, Cheltenham.