A gun Fired by Electricity.
--At Edinburg, a wire has been stretched between Edinburg Castle and the Calton Hill, 4,000 feet long, which fires a gun at the Castle daily at 1 o'clock. The objection to firing a gun at the observatory at Calton Hill was, that it would derange the instruments there. Accordingly a wire was stretched clear across the city without a rest. The electric current passing on it carries a clock at the Castle, which at 1 o'clock drops a weight that discharges the gun.