306 APPENDIX. [No. XXII. 



time deeply cut, the metal must be aggregated very carefully, otherwise 

 the metal grows on each side of the holder of the mould, and a slit is 

 left down the centre of the metal. In some cases this would be a fatal 

 inconvenience, and, where it is indispensable to avoid it, we use a feeble 

 battery power, with a stronger solution of sulphate of copper in the pre- 

 cipitating trough. 



All depositions in electro-moulds require for the highest perfection 

 the utmost care. It would be tedious to the Society to dwell upon all the 

 little points which require attention. Nevertheless, with proper care, no 

 mode of duplication has ever been devised which is attended with similar 

 identity. In all our electro-casts, whenever the most trifling air-bubble is 

 found, it is thrown out directly, as the few halfpence required as the cost 

 of the deposit of a small quantity of copper is nothing as compared with 

 the supply of perfect notes to the public. 



Although circumstances have led me to study more especially electro- 

 metallurgic operations, yet it is important that electricity should take its 

 proper place, and not be pressed into our service on every occasion, 

 whether it be suitable or not. In the bank-note it was a matter of debate 

 whether in some parts the steel die and punch should not be used, but for 

 various reasons it was decided to use a steel original, with lead moulds, for 

 electro-casts. There are some cases, however, in which the punch-and-die 

 system, or even the transfer system of Perkins, might be advantageously 

 applied in the typographical art. 



The electro-casts, when ready for printing, are mounted on solid brass 

 blocks, and many tools had to be constructed for this purpose. In this 

 detail there is involved the difference between making and manufacturing, 

 the formation of one article and the production of an infinite number. By 

 this system of tools, if any part of a forme is damaged, another piece is 

 immediately inserted. The same screw-holes in the plate and the same 

 screws are used for the new piece ; and, by every portion being made to one 

 gauge, an exactness is given to the system which it would have been im- 

 possible to have obtained by leaving such details to the caprice or judgment 

 of the workmen. By this system every part of the note is maintained in 

 exactly the same relative position, and thus identity in the form of the note 

 is absolutely secured. At the Bank a large stock of electrotype plates are 

 always ready to be mounted at a moment's notice, and if one happens to be 

 accidentally damaged, another is ready for insertion in precisely the same 

 place as that which preceded it. The electro-copper is so durable that 

 there is scarcely any limit to its wear, and at the * Times ' newspaper one 

 cast is said to have printed nearly 20,000,000, and yet not to have been 

 completely worn out. The limit to the duration of electro-casts for the 

 purposes of the bank-note has yet to be discovered, as above a million have 

 been printed with no perceptible effect. This duration alone is a matter 

 of considerable importance, as by it 'a constant identity is more particu- 

 larly insured. 



There is, perhaps, no part of the process of the manufacture of the 

 note of more importance, and more replete with curious interest, than the 

 production of the paper, by Mr. Portal, on which it is printed. The mill 

 is situated in Hampshire, on the river Test, and this beautiful stream 

 supplies the water to drive the machinery necessary for the production 

 of the paper. 



