CHRONOGRAPH, Locxx's ELECTRO C. This apparatus, for which an appropria tion was made by Congress, has been put in operation at the National Observa tory Washington.
The clock case is of fine Italian marble, ornamented with glass panels, set in silver sashes. The dial and hands are like those of an ordinary clock, but the dial is cut out and made a skeleton, for the purpose of giving access to the elec trical works behind it. The pendulum is made throughout of glass ; to compen sate for the expansion even of glass' by heat, the weight of the pendulum con sists of four large glass tubes, placed side by side, like organ pipes, all filled four or five inches deep with quicksilver. The suspension of thepend.ulum con sists of hardened steel cylinders, rolling on jewelled planes made of polished chrysolite. The mechanism by which the electrical contact surfaces are kept clean and bright is very ingenious and was suggested to Dr. Locke by Prof. House of New York. It consists of a small platinum cylinder which is kept revolving with a wiper to keep it clean. This cylinder has also a longitudinal mo tion, which by reciprocation makes the electrical contacts, which occur every second, travel in a spiral, which also re volves. The result is, that the contacts
are made every second for 36 days with out occuring twice in the same place ; and even then it is a mere chance if the contacts are recommenced in the same track.
Every time a contact is made a slight mark is left, by electrical action, on the platinum surface ; and when the spiral revolution has been completed, the cylin der is marked all over its surface by geo metric intersections.
The clock contains a duplicate interrup ter or electrotome, which maybe brought into action when desired. It consists of a little tilt-hammer, pivoted concentri cally with the pendulum, and lifted by a little arm, or its equivalent, projecting from the pendulum itself.
No less than four patents have been recently taken out in England for im provements in Clocks moved by Electri city. The first Electric Clock known was invented in 1615, by a German named Buzengeiger. This was a local clock.
The first Electric Clock to move in unison any number however distant, was inven ted by Bain in 1840. Since then there have been a great number of modifica tions such as combining a register' with the clock, which is a most important im provement.