CHAPTER VIII. MAUDSLEY'S PRIVATE ASSISTANT.

On the morning of Monday, the 30th of May 1829, I commenced my regular attendance at Mr. Maudsley's work shop. My first job was to assist him in making some modifications in the details of a machine which he had contrived some years before for generating original screws. I use the word " generating " as being most appropriate to express the objects and results of one of Mr. Maudsley's most original inventions.

It consisted in the employment of a knife-edged hardened steel instrument, so arranged as to be set at any required angle, and its edge caused to penetrate the surface of a cylindrical bar of soft steel or brass. This bar being revolved under the incisive action of the angularly placed knife-edged instrument, it thus received a continuous spiral groove cut into its surface. It was thus in the condition of a rudimentary screw ; the pitch, or interval between the threads, being determined by the greater or less angle of obliquity at which the knife-edged instrument was set with respect to the axis of the cylindrical bars revolving under its incisive action.