In Fig. 12 I show a modification of my invention, wherein, instead of having the balance-levers F, F¹ arranged side by side, they are superposed one above the other, in this case a plurality of knife-bars E, E¹ also being superposed one above the other, the expansion strips G, G¹, etc. (in this case shown as formed of wires or rods), and balance-levers being arranged in the same plane, somewhat in the nature of a coiled spring, the coil shaft being indicated at J and the coil lever at I, to which are connected the end expansion strips G, G^{x}, and the weight K¹ for placing the coil under tension. By this arrangement of balance-levers and expansion strips, in the same plane, much economy of space is effected, and when desired, a great number of such coils may be suspended upon the series of knife-bars. In Fig. 12ª I show two such coils connected in series, the terminal expansion strip G^{x} of the front coil being connected to one end of the lever I, and the opposite terminal G of that coil being connected to the shortest one of the rear set of levers F^{1ª}, the terminal G^{y} of the rear set being connected to the other end of the lever I. Thus two or more such coils may be connected, and the force of expansion and contraction of the combined coils transmitted to the lever I. When a number of such combined coils are suspended from the knife-bars E, E¹, the levers connecting their respective terminals may be themselves connected by a system of compound levers such, for example, as shown in Fig. 13, to be hereinafter referred to. Referring now to Figs. 13 to 20 inclusive. These figures illustrate another form of the invention whereby not only the power-storage device of the preceding [Illustration: _Fig. 6._ _Fig. 7._ BANGERTER’S PERPETUAL TIME CLOCK] figures may be dispensed with, but also the main spring of the clock there shown, both of these elements being supplanted by apparatus effecting the raising and lowering of weights (in this instance shown in the form of balls), the force of expansion and contraction of the coils being utilized to operate a rotary member which elevates a series of weights and discharges the same into a storage receiver, the clock (or other machine) being operated through the energy so stored and given up by the falling of said weights. As illustrated in said figures, this feature of the invention consists of a frame, indicated in whole at 10, located about midway the length of the expansion coils shown in Fig. 1, and it may be supported by securing it to the uprights C, C¹, or in any other suitable manner. Said frame comprises two horizontally disposed longitudinal framing members, 10ª, 10^{b}, which are connected at each end by cross-bars (not shown).