THE TRANSATLANTIC LONGITUDE. 87 



Oct. 25. 



Oct. 28. 





A. Induced 



CURRENT. 







Posil 



live signals. 



Negative 



signals. 



Mean. 



No. 



X1 + X2 



No. 



Xj + X2 



Xi + X2 



10 



0'.648 



8 



0'.659 



0».653 



10 



.617 



10 



.675 



646 



10 



.594 



10 



.577 



.584 



30 



0.620 



28 



0.635 



0.627 



9 



0.T94 



9 



0.707 



0.750 



9 



.691 



10 



.667 



.679 



10 



.637 



9 



.627 



.632 



28 



0.705 



28 



0.667 



0.686 



Let us now consider the experiments made without any earth-connection what- 

 ever, and first those of November 5 and 16, on which occasions the battery-power 

 at the two stations was the same. Each station sent signals with a battery of 3 

 Minotti's cells on the 5th, and 4 on. the 16th, receiving them with its battery dis- 

 connected. The circumstances at the two stations were as nearly identical as pos- 

 sible, and the mean interval consumed in the transmission of the signals appears 

 to have been 0^.29 on the former, and 0\26 on the latter occasion. 



With a battery of 3 Minotti's cells, each possessing a tension of 0.84 of a volt, 

 and incapable of generating more than 110 farads to the second when circuit Avas 

 made through earth and one cable only, the maximum permanent current would 

 not exceed 168 farads in the joined cables, and to develop nine-tenths of this cur- 

 rent more than 1^^ second would be needed. With 3 Daniell's cells the maximum 

 current would not exceed 185 farads. Assuredly we cannot suppose that in the lapse 

 of three-tenths of a second, when not more than one-seventh of this current had been 

 developed at the farther station, this battery could have charged the two joined 

 cables, each of which possessed an electrostatic capacity of more than 650 farads. 

 Hence the impulse upon which the transmission of the signal depends must have 

 been propagated along the conductor by some other means than by charging its 

 successive parts electrically ; i. e., fully, and in the ordinary sense of this expression. 

 The 30 farads, more or less, which could have been generated before the signal 

 arrived at the distant extremity of the cables, would have been consumed in charg- 

 ing the first six or seven hundredths of the conductor. 



During my stay in Valencia, messages were effectively and distinctly transmitted 

 in each direction by the use of an electromotor formed by a small percussion-cap 

 containing moistened sand, upon which rested a particle of zinc. The current 

 here evolved could scarcely have amounted to more than six or seven farads, so 

 that nearly two minutes would have been requisite for charging one cable ; yet the 

 transmission-time was certainly small, although it was not definitely measured. 



The experiments without earth-connection on November 6 and 9, diff'ered from 

 those of the 5th and 6th, only in that the Newfoundland battery consisted of ten 

 cells instead of the same number as was employed at Valencia. The mean times 

 of transmission were respectively 0\25 and 0'.24, indicating an increase of speed 

 with the increase of electromotive power. And, so far as the experiments on these 



