Description of the American electro magnetic telegraph : now in operation between the cities of Washington and Baltimore / by Alfred Vail.

  • Vail, Alfred.
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: Description of the American electro magnetic telegraph : now in operation between the cities of Washington and Baltimore / by Alfred Vail. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    21/26
    tion wheel; ihis lias released the clock work, which, through the agency of the weight, has commenced running, and the two rollers have supplied the pen with paper. But, as only one touch of the key has been made, the clock work soon stops again, if no other touches are made, by the action of the break upon the friction wheel. This shows the whole operation of the Telegraph, in making a single dot by a single touch of the key. In order now to explain more fully the ope- ration of the steel pen points upon the paper, which is in contact with the grooved roller, let there be made four touches at the key; this will be suf- ficient to start the clock work, and allow the paper to have attained a uniform rate ; then let six touches be made at the key. The contact has been made six times and broken six times. Each time it is closed, the electro mag- net, as heretofore explained, attracts to it, with considerable force, the arma- ture of the pen lever, carrying up the steel pen points against the paper, 2, under the steel roller, Si The three points of the pen, falling into the three corresponding grooves of the roller, carry the paper with them and indent it,* at each contact. There then appear upon the paper, as it passes out from under the rollers, six indentations, as if it had been pressed upon by a blunted point, such as the end of a knitting needle would be sup- posed to make, wdien pressed upon paper, placed over a shallow hole, but in such a manner as not to pass through the paper, but raising the surface, as in the printing for the blind. These indentations of the paper are the mark- ing of the pen, but varied in the manner now to be described. By examining the telegraphic alphabet, the characters will be found to be made up of dots : short and long lines—and short and long spaces. A single touch of the key, answers to a single dot on the paper of the register; which represents the letter, E. One touch of me key prolonged, that is, the con- tact at the key continued for about the time required to make two dots, pro- * The first working model of the Telegraph was furnished with a lead pencil, for writing its characters upon paper. This was found to require too much attention, as it needed frequent sharpening, and in other respects was found inferior to a pen of peculiar construction, which was afterwards substituted. This pen was supplied with ink from a reservoir attached to it. It answered well, so long as care was taken to keep up a proper supply of ink, which, from the character of the letters, and sometimes the rapid, and at others the slow rate of writing, was found to be difficult and troublesome. And then again, if the pen ceased writing for a little time, the ink evaporated and left a sediment in the pen, requiring it to be cleaned, before it was again in writing order. These difficulties turned the attention of the inventor to other modes of writing, differing from the two previous modes. A variety of experiments were made, and among 'them, one upon the principle of the manifold letter writers ; and which answered the purpose very well, for a short time. This plan was also found objectionable, and after much time and expense expended upon it, it was thrown aside for the present mode of marking the telegraphic letter. This mode has been found to answer in every respect all that could be de- sired. It produces an impression upon the paper, not to be mistaken. It is clean, and the points making the impression being of the very hardest steel, do not wear, and renders the writ- ing apparatus always ready for use.