Crystal Palace International Electric Exhibition 1881-82

56 drivers, and signalmen, and the localisation of trains whilst at full speed. Gallery at bach of Concert Room. 149 .—I. Probeet & J. Steljes (School of Telegraphy), Moorgate Street Buildings, E.C.—A Single or Reversing Current Key. Small-play and one set of batteries were the special features aimed at when this key was devised, in 1874. It consists of two brass bars insulated longitudinally and representing line and earth. The bar on the right of the insulator is the same as that of an ordinary S. C. key; but the one on the left has a parallel steel spring secured to its lower surface, whose relative contacts on the base, front, and rear are adjacent to those of the first bar. Vertical screws regulate the space between the ends of spring and contact studs; these, in conjunction with the adjusting screw on the other side, admit of of an inch play being obtained. A switch, enables the operator to send reverse currents as in the double-current system, and, when in the usual receive position, is also right for single-current working. An Automatic Gumming Apparatus, for use with the Hughes type printer, 1871. An endless cord connects a power of the printer with a friction pulley on the same axis as a boxwood roller, whose half section turns in a reservoir containing gum. The reservoir can be raised or lowered at will. A scraper frees the roller of superfluous gum. The slip is guided between, and, when i’eleased by the printing lever, moved by two rollers, after which, it slides over a curved plate with rounded edge. The gumming system is easily attached to the printer; and a simple adjustment is provided to regulate the tension of the driving-cord. With, tweezers and scissors the gummed slip is affixed to the message form. Rastern Gallery. 150 .—F. Murray Rogers, 21, Finsbury Pavement, E.C. Needle Sounder, for calling attention at will, or audibly repro- ducing the deflection of the needle. Railway Station Indicator for local lines (the indicator is worked automatically by the train on entering station, and shows the station arrived at in each compartment). Rotating Carbon Relay, contact sticking of the tongue being entirely overcome by fresh surface exposed at each contact; Electric Bells, Pushes, Switches. Southern Gallery. 151 .—Rustless and General Iron Company, 3, Queen Street Place, Cannon Street, E.C. Telegraph Poles and Fittings. Rastern Gallery. 152 .—Max Sabel, 2, Coleman Street Buildings, Moorgate Street, E.C. Agent for C. Milchsack & Co., Gladbach, Rhenish