needle for making signals. But none of these efforts had advanced beyond the experimental stage, and they were only of historical value. They illustrate the general principle that a great discovery hardly ever springs from the thought of a single man. But the fact that there were preceding tentatives does not diminish the fame of the man who gathers up and combines the previous results and completes what they had left unfinished. Weber was the first who established a permanent workable telegraph line, and thereby demonstrated the practical value of the electric telegraph. Weber's house in the city was connected with the astronomical and magnetic observatories by a line between three and four kilometres (over two miles) in length. The signals were made by the deviations of the needle of a galvanometer to the right and left and were interpreted according to a conventional alphabet. The use of interrupted or reversed currents did not permit the transmission of more than one or two words a minute, but the speed was increased to seven or eight words by the use of induced currents.
The following first notice of this telegraphic connection was published in one of the numbers of the Göttingischen gelehrten Anzeigen (or Göttingen Scientific Notes) for 1834: "We can not omit to mention an important and, in its way, unique feature in close connection with the arrangements we have described [of the Physical Observatory], which we owe to our Prof. Weber. He last year stretched a double connecting wire from the cabinet of physics over the houses of the city to the observatory; in this a grand galvanic chain is established, in which the current is carried through about nine thousand feet of wire. The wire of the chain is chiefly copper wire, known in the trade as No. 3. The certainty and exactness with which one can control by means of the commutator the direction of the current and the movement of the needle depending upon it were demonstrated last year by successful application to telegraphic signalizing of whole words and short phrases. There is no doubt that it will be possible to establish immediate telegraphic communication between two stations at considerable distances from one another."
Weber's general magnetic and electrical researches, by which his place in the history of science is most conspicuously marked, are described in the Resultate aus den Beobachtungen des magnetischen Vereins (Results from the Observations of the Magnetic Union), published by Gauss and Weber from 1837 to 1843, and in Weber's Elektrodynamische Maasbestimmungen (Electrodynamic Measurements), published from 1846 to 1874. Of these, M. Mascart says that "the thought of measures in mechanical unities was naturally applicable to the reactions which take place between conductors traversed by electric currents and between cur-
