_Record-Making and Manufacture._--Phonographic records are of two shapes, the cylindrical and the flat, the latter cut with a volute groove continuously diminishing in diameter from the circumference to the centre. Flat records are used in the Gramophone--a reproducing machine only. Their manufacture is effected by first of all making a record on a sheet of zinc coated with a very thin film of wax, from which the sharp steel point moved by the recording diaphragm removes small portions, baring the zinc underneath. The plate is then flooded with an acid solution, which eats into the bared patches, but does not affect the parts still covered with wax. The etching complete, the wax is removed entirely, and a cast or electrotype _negative_ record made from the zinc plate. The indentations of the original are in this represented by excrescences of like size; and when the negative block is pressed hard down on to a properly prepared disc of vulcanite or celluloid, the latter is indented in a manner that reproduces exactly the tones received on the “master” record. Cylindrical records are made in two ways, by moulding or by copying. The second process is extremely simple. The “master” cylinder is placed on a machine which also rotates a blank cylinder at a short distance from and parallel to the first. Over the “master” record passes a reproducing point, which is connected by delicate levers to a cutting point resting on the “blank,” so that every movement of the one produces a corresponding movement of the other. This method, though accurate in its results, is comparatively slow. The _moulding_ process is therefore becoming the more general of the two. Edison has recently introduced a most beautiful process for obtaining negative moulds from wax positives. Owing to its shape, a zinc cylinder could not be treated like a flat disc, as, the negative made, it could not be detached without cutting. Edison, therefore, with characteristic perseverance, sought a way of electrotyping the wax, which, being a non-conductor of electricity, would not receive a deposit of metal. The problem was how to deposit on it.