tlantic coast line.--_Bennington (Vt.) Banner._

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COWPER'S WRITING TELEGRAPH.

The most recent of the brilliant series of telegraphic marvels which
has from time to time, and especially of late, engaged the attention
of the world, is the "telegraphic pen" of Mr. E. A. Cowper, the well
known engineer of Great George street, Westminster. This ingenious
apparatus, which constitutes the first real telegraph, was publicly
shown by its inventor at the meeting of the Society of Telegraph
Engineers on Wednesday, February 26.

There had been no lack of copying telegraphs hitherto. We have
Bakewell's, Casselli's, Meyer's, and D'Arlincourt's, so recently tried
at our General Post Office by Mr. Preece. All of these instruments
telegraph an almost perfect copy of the writing or sketch submitted to
them by means of synchronous mechanism. But the process is necessarily
complex and slow; whereas by the new device a person may take the
writing pencil in his hand, and himself transmit his message in the
act of writing it.

The principle which guided Mr. Cowper to a solution of the problem
which he has successfully overcome, is the well known mathematical
fact that the position of any point in a curve can be determined by
its distance from two rectangular co-ordinates. It follows, then, that
every position of the point of a pencil, stylus, or pen, as it forms a
letter, can be determined by its distance from two fixed lines, say
the adjacent edges of the paper. Moreover it is obvious that if these
distances could be transmitted by telegraph and recombined so as to
give a resultant motion to a duplicate pen, a duplicate copy of the
original writing would be produced. But inasmuch as the writing stylus
moves continuously over the paper, the process of transmission would
require to be a continuous one; that is to say, the current traversing
the telegraph line, and conveying the distances in question (or what
comes to the same thing, the up and down, and direct sidelong ranges
of the stylus) would require to vary continuously in accordance with
the range to be transmitted.

Mr. Cowper effects this by employing two separate telegraphic
circuits, each with its own wire, battery, sending, and receiving
apparatus. One of these circuits is made to transmit the up and down
component writing of the pencil's motion, while the other
simultaneously transmits its sidelong component. At the receiving