The apparatus for Impact experiments, which was exhibited to the Society on 20th February 1888, has been greatly improved by the substitution of a very true slab of plate-glass, thinly covered with printing-ink, for the sheet of cartridge paper. The record is made by a needle-point which projects from the falling body, and which is kept in constant contact with the plate by means of a light spring. The time of rotation of the plate is given by a tuning-fork, with a small bristle attached, which is kept in vibration by a periodic current, and records alongside of the other tracings.