It is erroneously supposed by many that a self-windiug clock must ohtain its motive power from electrical action and thereby be subject to the uiany objections and liindrances resulting trom an eotire dependence on a constant curiest. "The motive power of our clock," said the genial agent of a large concern on Dey street to a Mail and E xpress reporter, ia "derived trom the action of a fine spring, as in the ordinary clock. The term self-wlnding resulta from the lollowiiitf: Two sinall colls of a battery are placed in the top of the case and connected vvith a motor secured to the lower part of the movement. As the centre wheel, diiven bv the unwinding of the spring, makes one revolution around the hub lt tirinas up a loóse arm which slips under a ftationery projecting arm fastened to the train plate. The moment the contact takes place the circuit is closed, and the action of the little motor rotates the barrel containing the spring one revolution from left to right, and winds up just as mncli of the sprint: as lias been required to run the clock during the lust sixty minutes. The spring barrel itseïf carries an arm which slittes the loose arm from under the projecting arm, tlms breaking the circuit; the same action is repeated every sixty minutes. To those familiar wltli mechanism it will be quite apparent how simple and practical is this device. The invention lieg in brlnglng a motor nd clockwork together in a timepiece, and is not limlted to any particular device. Experimenta prove that a motor as constructed for the purose can be run for one year at an expense of loss than 20 opnts"; henee a clock may be sealed up and left to itself for a period of at least one year with a certalnty of closer time durinp; that period than can be secured by any other known method of giving time. In short, u common clock constructfd on this principie has been found to keep as accurate time as one of the hlgher grades with gravity escapements, run by the old methods." Self-winiiing clocks are in great demaml by railway corporatlons, some of wliich now have them in operation, notably the New York Central and Hudson Kiver Railroad Compauy and the Ii.iltimoie and Ohio Telegraph Oompaoy, in thelr offices in this city.