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POPULAR SCIENCE REVIEW. 
be very successful, and admits of a vastly increased speed. 
In Professor Wheatstone's system the dashes of the Morse 
alphabet are represented by dots placed on the right hand of 
the paper ribbon, and the dots by similar marks on its left. 
Another line in the centre of the ribbon serves to form the 
spaces between the letters and words. This arrangement 
permits the perforating apparatus to be very much simplified, 
and to be manipulated with comparative ease. The apparatus 
by means of which the punched slip transmits the message 
is on the principle of the Jacquard loom. In it three wires 
are placed in a position precisely similar to that of the punches 
in the perforating apparatus. They he on the edge of an 
eccentric wheel, which at each revolution presses them against 
the paper ribbon. If a hole be opposite the punch, it passes 
through it, touching the metal wheel and putting the battery 
in action. One wire sends positive, the other negative cur- 
rents, which act upon separate electro-magnets in the receiving- 
instrument, so as to reproduce the signs in ink. 
It is obvious that a similar effect can be obtained by etching 
the Morse characters upon a plate of metal covered with 
varnish, or by writing them in insulating ink upon a piece of 
metallic foil or silvered paper ; and by chemical decomposition, 
Roman letters, or even a sufficiently bold handwriting-, may 
be copied from the foil upon a sheet of prepared paper, by 
ruling a series of lines across the two with metallic pencils, 
connected with each other and with a battery. 
When the sending pencil is drawn across that part of the 
foil on which nothing is written, and which therefore conducts 
uniformly, the receiving pencil will produce a straight line 
upon the moistened paper ; but when the sending- pencil moves 
across the writing , the current will be cut off by the insulating 
ink, producing corresponding breaks in the line formed by the 
other pencil ; if the two pencils are so connected as to be 
capable of being moved uniformly over their respective sheets, 
and if a series of parallel lines be drawn closely together by 
them, they will form a copy of the original in a species of line 
engraving or etching. 
Many years since, Mr. Bakewell invented a copying appa- 
ratus founded upon this principle, by which fac- similes of 
handwriting were transmitted from London to Brighton as 
early as 1848. 
The so-called Pantelegraph of the Abbe Caselli is really 
worthy the name it bears, for it transmits Chinese or Persian 
characters as readily as our ordinary letters, and reproduces a 
correspondent's autograph, or even his portrait if required. 
The despatch is written in ordinary ink upon silvered paper, 
and by a peculiar arrangement of batteries the copy is pro- 
duced in blue upon a white ground. 
