Fig. 1 is an end view of the apparatus _a_, _a_, are the bearings, top and bottom, for the vertical shaft _b_, which bearings are to be so constructed as to produce the least possible amount of friction. _c_ is a large drum furnished with radial plates or fans, some of the plates being so arranged as to slope down towards the bottom plate, thus forming, as it were, a series of boxes decreasing in their transverse dimensions as they approach the boss. This drum is to be put in motion by means of a current of air directed through the pipes _d_ and _e_, from the two pairs of double bellows _f_ and _g_. _h_ is a worm fixed on the vertical shaft by means of a tightening screw, or in any other convenient way, taking into the worm wheel _i_ on the horizontal crankshaft _j_, supported in bearings _k_, _k_. The cranks _l_, _l_, work the bellows by connecting rods _m_, _m_; _n_ is a spur wheel taking into a pinion _o_, on the axle of which is a winch handle _p_, for starting the apparatus. What I claim as my peculiar right is, the impulsion of a current of air against the fans of a drum (as that at _c_) through pipes, as at _d_ and _e_, for the purposes of a motive power, together with a certain arrangement of mechanism, by means of which the action first induced shall be kept up. Läserson's Device In 1860 Marc Antoine F. Mennons, of Paris, applied on behalf of Louis Diodor Läserson of Moscow, Russia, for, and obtained, a British patent on "Certain Improvements in the Production of Motive Power, and in the Apparatus Connected Therewith." He described the essentials of his device as follows: [Illustration]