For some days past I have been in the habit of observing atmospheric electricity about one o'clock, with the view of ascertaining whether the concussion produced by the time-gun has, as I suspected from an experiment of ten years ago, an effect on the amount collected by the water dropper. For several successive days the atmospheric charge was small and only slowly variable, and uniformly on these occasions I found a sudden slight increase of the deflection of the electrometer (whether it was originally positive or negative) to occur simultaneously with the sound, precisely the result obtained in the single experiment of date 21st May 1864. It appears to be most probably due to mere shaking of the instruments.