90 THE TRANSATLANTIC LONGITUDE. 



foundland ; but, contrary to my expectations, only two of the ten positive signals 

 from Newfoundland, were perceptible upon the Valencia galvanometer, and these 

 were but weakly indicated, the needle being much agitated. 



Valencia. Newfoundland. 



Cable of 1866 - 



Cable of 1865 ■ 



The results of the recorded signals give 0'.26. as the transmission-time through 

 one cable with earth-return, when the ground-connection was made with the zinc, 

 and 0'.27 when it was made with the middle of the battery; the former corres- 

 ponding to the use of four cells, at one station only, and the latter to two cells at 

 each station. 



Passing next to the consideration of the velocity of signals given by closing and 

 interrupting the circuit, which for convenience we will call " make-circuit" and 

 " break-circuit" signals, we have some data for the investigation from the first and 

 third series of experiments. For the first series the battery was at Valencia, and 

 the signals from Newfoundland were necessarily given by making and breaking the 

 circuit for the battery at the other station, or, in the language of telegraphers, send- 

 ing against the current. For the third series, the inverse was the case, and the 

 Valencia signals were sent by means of the current from Newfoundland. In both 

 instances the signals from the battery-station were given in the usual way by the 

 alternation of opposite currents. That such an arrangement was ill adapted for any 

 important electrical investigation is palpable ; but such few experiments as were made 

 were of course entirely subordinate to the object of our expedition, and were, as 

 will be seen from the programme, very roughly indicated in advance. The totally 

 different character of the methods and appliances from those which had come 

 within the previous experience of our longitude-parties, as well as the very different 

 nomenclature, rendered telegraphic instructions difficult, ambiguous, and, as the 

 event proved, often ineffective. The circumstances under which our few simple 

 trials were made were embarrassing, in spite of the cordial interest and friendly aid 

 of the telegraphic staffs on both sides of the ocean. The cables were in continual 

 requisition for commercial purposes, although all facilities were accorded which I 

 could conscientiously ask. It nevertheless appeared desirable to make such few 

 essays at measuring the time of transmission as opportunity conveniently allowed, 

 in the hope that something of interest might prove deducible. And it wiU be 

 perceived that our own experience could not be rendered available at the time, 

 inasmuch as all inferences must be derived from the measurement and collation of 

 chronographic records, which could only be brought into juxtaposition by some 

 3000 miles of transportation. 



Our data, thus obtained, for the relative velocity of the make-circuit and break- 



