COPYING MACHINES. Copying Ma chines are extensively used in mercantile es tablishments for producing duplicates of letters, invoices, and other manuscript papers. The most simple contrivance acts by trans ferring, by means of a rolling or screw press, a portion of the ink with which a letter is written to the surface of a sheet of blank paper prepared to receive it by damping. The transfer thus obtained is of course the reverse of the original letter, and, unless it be taken on paper so thin and transparent that it may be read through it, it must be read backwards. Watt's copying-press was a contrivance for obtaining transfers of this kind upon thin un sized paper, wetted, and then placed between two woollen cloths, which absorbed all un necessary moisture. Elegant screw presses of iron are manufactured for this purpose ; some having the power applied solely by means of a screw, turned by a transverse bar or lever, or by a cross or wheel-shaped handle; while others have also a contrivance for in , creasing the pressure beyond what can be conveniently applied by the simple turning of the screw. In some cases, letters intended for transferring by the copying-press are written with an ink made for the purpose ; and when common ink is used it may be thickened by adding a little sugar to it. Transfers are also taken from the pages of a manuscript book prepared for the purpose, a sheet of dry oiled paper being placed over the damp sheet to prevent the transmission of the moisture.
Contrivances for enabling a person to write with two pens or pencils at once, on different sheets of paper, on the principle of the Pax Tooraprr,have been tried as copying-machines, but they are too complicated for ordinary use.
All such machines, and perhaps even the copying press, are far surpassed in conveni ence by the Manifold Writer. In this appa. ratus a sheet of paper blackened on both sides with printers' ink, and dried for five or six weeks between sheets of blotting-paper, or covered with some other black composition which will come off when pressed hard, but will not move with a slight degree of pressure or friction, is laid between two sheets of thin writing-paper, and the whole is placed upon a smooth copper or pewter plate. The letter is then written firmly on the upper sheet of paper with an agate style or point, the pres sure of which causes the blackened paper to produce two impressions of the writing, one, which is read through the paper, upon the under side of the sheet directly acted upon by the style, and the other upon the upper side of the lower sheet. More than two impres. sions of the writing may be obtained by using two or more sheets of blackened paper, inter posed between several sheets of thin white paper. This apparatus is conveniently fitted up in a small portfolio, and occupies no more room than en ordinary writing-case.
In a machine recently registered by Messrs.' Mordan, a stamping press' is combined with an ordinary copying machine. When worked in the customary way, the platten rises with I the screw, leaving a space beneath it for the copying process ; but by a little adjustment the screw is raised without the platten, leaving a die and counterdie in proper position for stamping any device on letters, envelopes, or papers.