10 



that it would copy medals. These suppositions are rendered the 

 more probable to me by the way in which Mr. Mason related the 

 matter to me. He said Mr. Gobrecht invited him into his pri- 

 vate room, showed him a machine of his invention for ruling 

 medals, and exhibited as a specimen of its work a copy of the 

 Alexander medal. Thus was conveyed to my mind the belief, 

 that this was the first time that Mr. Mason had seen or heard of 



medal ruling. 



It is remarkable that the Rose Engine, with one of its move- 

 ments so identical with that of medal ruling, should have been 

 so long in use without leading to that art. Perhaps a simple de- 

 scription of its action in the Rose Engine and in the ruling ma- 

 chine, may not be out of place here. The Rose Engine has two 

 principal movements ; one circular, the other lineal. The latter 

 is adapted to ruling waved lines, which, in fact, it does in the 

 Rose Engine. A waved surface of hard metal is fixed to the 

 machine, a tracer is adjusted to the model, and a cutter to the 

 plate that is to be engraved. The machine is put in motion, 

 when a waved line is cut on the plate. The plate is then ad- 

 vanced a step, the motion is repeated and another line is cut. 

 Thus a series of lines is continued until the work is done ; and 

 as the tracer passes always on the same line over the model, the 

 lines on the plate are similar. To show more clearly the result 

 of this movement in the Rose Engine and in the ruling machine, 

 I have prepared two specimens, one from each. 



I have taken for a model the word "Londini" in raised letters. 

 The first series is after the manner of the Rose Engine, the plate 

 alone being moved, the tracer passing always on the same line, 

 which you may perceive is just where the right hand thin stroke 

 of the N joins the thick one. The model is then fixed to the 

 carriage, and made to move with the plate. The tracer is placed 

 on the plane, a few lines above the letters ; the ruling is com- 

 menced and carried on until the tracer comes on the same line 

 on which it acted during the first series. The first series is 

 made up of one minute section of the model, and, consequently, 

 can give no indication of the device that may be on it. In the 

 second series, where the model moves with the plate, a different 

 section of the model is brought under the tracer at every line. 

 A course of minute sequent sections is marked on the plate, and, 

 these imbodied, show the device on the model. 



