"There is not a thought in any one of the foreign journals relative to the Telegraph which I had not expressed nearly five years ago, on my passage from France, to scientific friends; and when it is considered how quick a hint flies from mind to mind and is soon past all tracing back to the original suggester of the hint, it is certainly by no means improbable that the excitement on the subject in England has its origin from my giving the details of the plan of my Telegraph to some of the Englishmen or other fellow-passengers on board the ship, or to some of the many I have since made acquainted with it during the five years past." In this he was mistaken, for the English telegraph of Cooke and Wheatstone was quite different in principle, using the deflection, by a current of electricity, of a delicately adjusted needle to point to the letters of the alphabet. While this was in use in England for a number of years, it was gradually superseded by the Morse telegraph which proved its decided superiority. It is also worthy of note that in this letter, and in all future letters and articles, he, with pardonable pride, uses a capital T in speaking of his Telegraph. One of the most difficult of the problems which confront the historian who sincerely wishes to deal dispassionately with his subject is justly to apportion the credit which must be given to different workers in the same field of endeavor, and especially in that of invention; for every invention is but an improvement on something which has gone before. The sail-boat was an advance on the rude dugout propelled by paddles. The first clumsy steamboat seemed a marvel to those who had known no other propulsive power than that of the wind or the oar. The horse-drawn vehicle succeeded the litter and the palanquin, to be in turn followed by the locomotive; and so the telegraph, as a means of rapidly communicating intelligence between distant points, was the logical successor of the signal fire and the semaphore. In all of these improvements by man upon what man had before accomplished, the pioneer was not only dependent upon what his predecessors had achieved, but, in almost every case, was compelled to call to his assistance other workers to whom could be confided some of the minutiæ which were essential to the successful launching of the new enterprise.