MY years ago I ventured the opinion that the development of $he mechanical clock was hindered for many centuries by the general use of the Roman system of hours. I am more than ever convinced of this, It is perfectly well known that prior to the Christian era trains of gearing and other mechan~cal expedients were in use whereby the hand of a clock could be made to travel with uniform motion on a dial. There was. to be sure, no true mechanical escapement, but Cte~ibius had devised what I venture
... ised what I venture $o call a water escapement, which, under certain restricted conditions, performed the true function of that element of the modern clock. But the ingenuity of the times was not adequate to the produotion of the varying movement necessary to keep time in a system in which the length of the houm was constantly changing; and rn the clock waited many centuries untjl the system of hours was changed. Thissubject has been brought q u~t e forcibly to my mind by coming into the possession of a nuniber of German and Sviiss patents for clocks designed to keep Turkish time. I t appears Prom the specifications that the Turkish system of hours is practically identical with that of ancient Rome, the day commencing and ending with sunrise, and the middle being a t sunset, the two p e r i d s of day and night being divided into six hours each, which constantly vary in length with the change of season. I t is obviously impracticable to make u p a railroad time-table on such a system, or to accommodate it to numerous other requirernentsof modern social life; and therefore the wondrr is that anybody should think it worth while to construct a clock adapted $0 this system; but, as the patentees are in all cases residents of Gonutantinople, it may he inferred that, i n devising these clocks, &hey are endeavoring to minister to a felt want of that capital. The device employed is of the same character in all the patents, though i n some automatic, in others requiring frequent attention. It consists in so adjusting the governing member (pendulum or 'balance-wheel) as to give i t a faster or slower rate from month to month; that is to sag, in the winter months, when the period from sunrise to sunset is short, to quicken the action of the movement so that the hand shall pass i n proportionately less time over that portion of the dial which represents the hours of dayhght than it does i n summer, when the days are long. I t is obvious a t once that this does not accomplish the purpose sought for, and the infelence is natural that in the German and Swiss Patent Offices the question of utiliLy cannot have been raised on these applications. If the pendulum is adjulted to a slow heat in the month of June, when the hours from sunrise to sunset are long, it might measure Lime during the day, but that same slow beat will destroy its capability of measuring off the short hours of the night. A parallel statement is true for the month of Decernher. For this reason these inventious are useless, though they may serve the purpose of the patentees by imposing on the credulous Moslem. I t does not seem impossible in th? present state of the arts to construct a time-piece capable of marking off this kind of hours with remonable precision. The exactness of an astronomical clock or even of an ordinary kitchen clock would be unnecessary. But tlze inventions above referred to do not approach a solution of the problem, the key to which is to be found in a clock presented to this Government by that of Japan a t the close of the Centennial Exposition. Jn this the hand moves around the dial a t B uniform rate throughout the year, the adjustment for different masons being accomplished by shifting the figures on the d~a l . Et is many years since I have seen this clock, but, as I recollect it, the top of the dial repreeents sunrise and the bottom sunset, the half-circumference on each side being divided into five hours by a set of figures which can be shifted i n place as the seasons change so as to make the day hours long and the night hours short, and vice versa, the sunset hour being shifted also. I see no great disculty in producing this shifting of the sunset hour automatically to the right or left as the season may require, nor does it appear to me insurmountable lo connect the intermediate hours with the sunset hour so that they shall be shifted proportionately with it. With such a contrivance an hour-hand moving a t an equal rate over the dial would point to the true hour by Turkish time a t all seasons of the gear, day and night. I n fact, the problem seems to m e so easy of solution that I can only explain the non-appearance of such clocks in the market by the supposition that no actual denland exists for them.