116 Mr, Henry Bradbury May 11, 



properly understood. Up to within a short time it has been found 

 uncertain, difficult, tedious, expensive, and requiring great length 

 of time to obtain adequate results from it ; but Mr. Bradbury stated 

 that he had for the last two years devoted his energies to overcome 

 these difficulties, and that his experiments had been attended with 

 many practical advantages in the Art of Printing. On the table 

 before him he had a small electrotype apparatus, by which was pro- 

 duced a perfect electrotype cast of an impressed metal plate before 

 the audience in half an hour.* He stated, that one of his experiments 

 had been crowned with such success that he had reduced the opera- 

 tion of tlie battery and the decomposition trough to so rapid and 

 certain a result as to be able to duplicate the woodcuts contained in 

 a number of the Illustrated London News^ no matter what their 

 number or size, in the short space of twelve hours (ready in every 

 respect for the press), which he stated as his belief was one of the 

 greatest practical accomplishments that had ever been made in 

 any country in this branch of science ; the value of which to the 

 journal in question will be best understood when it is known, that 

 without this or other means (not yet discovered), the production of 

 the requisite number of copies in time for publication would be a 

 mechanical impossibility (so extensive is its circulation) since from 

 one set of engravings there is a limit to the number of impressions 

 that can be printed from one machine in a given time. 



The mode of printing these electrotype f plates of plants is the 

 same as in ordinary copper-plate printing, where the impression is 

 produced by passing the inked plate with the sheet of paper laid 

 upon it through a pair of rollers, one of which is covered with four 

 or five thicknesses of blanketing, which causes the peculiar raised 

 or embossed appearance of the impression. 



In such cases, where there are three, four, or more colours, for 

 instance, — as in flowering plants, having stems, roots, leaves, and 

 flowers, — the plan adopted in the inking of the plate is to apply the 

 darkest colour first, which generally happens to be the roots — the 

 superfluous colour is cleaned off, — the next darkest colour, such as 

 perhaps the colour of the stems, is then applied — the superfluous 

 colour of which is also cleared off, — this mode is continued until 

 every part of the plant in the copperplate has received its right 

 colour. In this state, before the plate is printed, the colours in the 

 different parts of the copper look as if the plant was imbedded in 

 copper. By putting the darkest colour in at the beginning, there is 

 less chance of smearing the lighter ones : the printer too is not only 



♦ In the afterpart of the evenuig Mr. Bradbury succeeded in producing thin 

 electro-plates of impressed plates in five minutes. 



f The copper deposited upon moulds by electro-galvanic agency, is pre- 

 cipitated in such inconceivably small atoms, that the defects previously referred 

 to in the surface of the lead plate, arc oX&o faithful h/ copied, but the surface of 

 copper funlikc that of lead) will allow of these defects being removed by the 

 aid of the burnisher, and a polished surface preserved. 



