193,421. Hasselberg, B. A. L., and Ostberg, K. G. Feb. 18, 1922, [Convention date]. Sheets and like elements, travelling.-Apparatus of the type having interchangeable advertising leaves moved consecutively and periodically in a cycle to and from a display position is constructed so as to be of small thickness and suitable for show-windows or tramcars, &c. A block of sheets 7, Fig. 2, of paper &c. bearing advertisements on both sides is contained in a glazed casing 1 at the top of which is a shifting roller 9 driven by side belts, from a continuously rotating shaft 8 and running clear of the block 7 and of the casing walls. On the shaft 8 is a gear wheel vacuum pump which reduces the air pressure in a chamber 34 in which is a port covered by a spring-pressed valve 20 on a piston 16. In the piston 16 is a port 18 connected to a free opening 17 at the bottom of the piston. As the pressure in the chamber 34 is reduced the external air pressure forces the piston 16 with valve 20 upwardly against its weight and the pressure of the spring 35 till the port 18, hitherto closed by the cylinder wall, enters an enlargement 19. Air then rushes in through the opening 17 and the piston stops. The in-rushing air detaches the front sheet of the block 7 and carries it against the opening 17, whereupon the piston again commences to rise, carrying the sheet till the side edges of the latter are gripped between the roller 9 and its driving belts. The sheet is then rapidly transferred round the roller 9 to the back of the block 7, being guided by a surface 32, an oblique edge 33, and a series of stirrups 13 arranged along a top bar 12. Removal of the sheet from the opening 17 destroys the vacuum in chamber 34 and the piston 16 falls to its original position. The opening 17 may be wider than the piston, and may consist of a number of orifices distributed along the edge of the sheet. It may also bear against the block 7 and be given an outward movement to separate the top sheet. An abutment 36 prevents other sheets being withdrawn by friction along with the front one. The display interval may be determined by adjusting the pressure of the spring 35 or the volume of the chamber 34. The sheets may be made visible from both sides of the apparatus, the members 8, 9 being then arranged vertically at the edges of the casing 1. The apparatus may be inclined about the axis of the roller 8, or may be suspended. The bottom of the casing 1 on which the block 7 rests may slope forwardly or backwardly, and the forward motion of the block can be inspected at corner apertures. The driving motor may be on the shaft 8 or at a distance therefrom, in which case a flexible shaft connection may be employed disposed within the vacuum conduit from the air pump on the motor. The Specification, as open to inspection under Sect. 91 (3) (a), describes the apparatus shown in Figs. 1, 6, 7, (Cancelled), in which a transfer roller 6 is driven intermittently and each sheet after reaching the front is pushed up till its edges are caught between the roller 6 and the belts 9 and taken round the roller to the back of the block, the top 13 of the casing acting as a guide. A plate 27, Fig. 7 (Cancelled) may be provided to form a slot wide enough to allow only one sheet at a time to pass up to the roller 6. To prevent the sheets assuming a permanent curve they are bent in the reverse direction by a flange 12 when passing down behind the block. Each ,sheet on leaving the roller 6 reaches its required position by its momentum, which may be supplemented by longitudinal grooves 25 cut in the roller 6 to form abutments which will engage the rear edge of the sheet and force it down. Parts of inner sides of the casing are inclined to align the sheets as they move gradually to the front. The means for pushing up the front sheet comprise a rubber-tipped V-spring 19, Fig. 6 (Cancelled) vertically slidable in guides and connected to a spring 23 which engages between the belt 9 and the pulley 10. The pulleys 10 are operated pneumatically, a motor and air-pump 29 supplying pressure to a conduit 38, which may act as an adjustable reservoir, and a valve 39 admitting air automatically at intervals to cylinders 52. The valve 39 contains a spring-pressed seating on a portion only of which the pressure is exerted before the valve is opened, after which the air acting on the whole of the seating keeps the valve open till the pressure is considerably reduced. Each cylinder 52 contains a piston 53 to which is attached a wire which passes round a pulley, by which it is gripped, and is connected to a long helical spring which serves to return the pulley and the piston 53 to their original positions when the charge of air has leaked past the piston 53. To the pulley is fixed a ratchet wheel which engages a pawl on a surrounding sleeve carrying a pin to which is fixed the outer end of a. spiral spring the inner end of which is attached to the pulley 10. The pin directly turns the pulley 10 by contact with a rubber stud thereon, and when the pin is stopped by a brake actuated by a bead on the wire the pulley, together with the belts 9 and roller 6 continue their motion by inertia, against the action of the spiral spring, till stopped by a second stud engaging the pin. The spiral spring then returns the pulley 10 and belt 9 through part of a revolution, thus providing the motion requisite to bring the springs 19 and 23 again to their lower position. In a modification the sheets are displayed on both sides of the apparatus. This subjectmatter does not appear in the Specification as accepted.