The original, once
inscribed in either manner upon the above-mentioned _tafroo_ or
gold-leaf, is placed upon a sheet of a species of linen, smoother than
paper, called _difra_. A current of electricity sent through the
former reproduces the writing exactly upon the latter, which has been
previously steeped in some chemical composition; the effect apparently
depending on the passage of the electricity through the untouched
metal, and its absolute interception by the ink, if I may so call it,
of the writing, which bites deeply into the leaf. This process can be
repeated almost _ad libitum_; and it is equally easy to take at any
time a fresh copy upon _tafroo_, which serves again for the
reproduction of any number of _difra_ copies. The book, for the
convenience of this mode of reproduction, consists of a single sheet,
generally from four to eight inches in breadth and of any length
required. The writing intended to be thus copied is always minute, and
is read for the most part through magnifying spectacles. A roller is
attached to each end of the sheet, and when not in use the latter is
wound round that attached to the conclusion.
Pages:
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172