10,219. Welte, B., Welte, E., and Welte, M., [trading as Welte & S÷hne, M.]. May 20, 1904, [date applied for under Patents Act, 1901]. Automatic instruments.-In pneumatic pianoplayers the striking of the keys is graduated by the regulation of the air suction either automatically from the tune sheet or by hand. The passage between the main bellows a, Fig. 1, and the regulating-bellows d is controlled by the slide valve c, which is connected by a cord passing over a pulley g to the bellows d, so that, for a given position of the pulley, the pressure remains constant in spite of variations in the amount of air required. The pressure, however, varies according to the position of the pulley g, which may be regulated directly by hand, or indirectly by the bellows e controlled by hand, or automatically by the regulation of the bellows e by the relay system shown in Fig. 2 and operated from the tune-sheet. A rapid closing of the bellows e, resulting in a sudden forte, is effected by the relay r' controlling the large pipe l; this condition is maintained by the action of the relay r3, which is always used in connexion with the former for forte passages. The relay r3 when used alone effects a gradual exhaustion of the bellows e through the very narrow pipe p, and thus provides a crescendo effect. A rapid opening of the bellows is produced by the relay r', which governs the opening of the orifice o by means of the pneumatic n, the relay r4 which disengages the crescendo relay being simultaneously actuated. A mezzo-forte effect is produced by the action of the relay r5, which governs the pneumatic h and interposes a stop i in the path of the roller g and holds it in a mid-position. Various different changes are produced by suitable operations of the several relays. The relays are maintained in their raised positions until the neighbouring relay is operated by means of the air passages t, v, thus rendering long holes in the tune-sheet unnecessary for this purpose.
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