Whenever any document to be sent by telegraph bears a seal, either private or official, it shall not be necessary for the operator in sending the same, to telegraph a description of the seal, or any words or device thereon, but the same may be expressed in the telegraphic copy by the letters "L.S.," or by the word "seal," and whenever any document bears a revenue stamp, it shall be sufficient to express the same in the telegraphic copy, by the word "stamp," without any other or further description thereof.