ON 



DETERMINATION OF TRANSATLANTIC LONGITUDE^ 



441 



IS 



then 



peated, from the first station to the second, and again fi 



the second to 



the first. 



II. The second cl 

 positive and negativ 

 one half of a second 



i of signals differs from the first class in two ways: 1. The 

 currents which are sent into the cable are continued for only 

 2. The observer records the moment when the light begins to 



move from the centre, towards the right or left end of the scale. This class of sig 

 may be written thus : 



(p») 



5 



(2P) 



5 



(P>) 



10 



(iV) 



5 



(P») 



5 



( J y»)j_(p*)_!2_(j\r«)i.(P»)±(iv«). 



III. In the third class of signals, alternating positive and negative currents, to ihe 

 number of six, and each of five seconds' duration, are sent at intervals often seconds 

 from the first station, and the moment is recorded at the other station when ihe light 

 upon the scale darts towards the centre. 



again 



centre. After an interval of fifteen seconds a sir 

 Then the same number of signals are despatched from t lie second 



to be 



ded at the first 



Afterwards, the whole operation is repeated fi 



the first 



the second, and also from the second to the first. This 



o 



f 



gnals in two groups may be written thus 



(-p 5 ) 



10 



(W) 



10 



(i») 



10 



(•tf 6 ) 



10 



(J») 



10 



(W) 



15 



(i*) 



10 



(^ s ) 



10 



(i*) 



10 



7T>\ 1 



o_(f*)2!(iV*). 





IV. The fourth class of signals differs from the third as follows. Four nlternating 



make a group, and 



groups 



The duration of each 



seconds. The interval between the end of one current and the beginning of the 

 is five seconds, and the interval between groups is ten seconds, thus : 



(-p 



10 \ 5 



(N 



10\ 5 



{P 



10\ 5 



(N 



10\ 5 



(p 



10\ 5 



(N 



10 



io_(P 10 ) ±(N l0 )±(P l0 )±{N l0 )± {P l «)±(N 



10 



It will be noticed that the signals which are recognized when Classes I, 1 II, and I V 

 are used, are discharge signals ; that is, that the moment is recorded when the am 

 tion of the battery current reaches the remote station, and the needle of the gal va- 



nometer suddenly returns to the 



On the other hand, when signals of Class II. 



- - employed, the moment is recorded when the needle begins to show the effect o 



the charge. The velocity with which the signal travels is diminished to a s hght extent 



by the resistance of the battery, and when the sending batteries at the »„ sta ,„„ 8 



transmission time derived from currents sent alternately from ,he 

 be vitiated to the extent of half this difference m the res.stance of 



are differe 

 two statioi 



, the 

 will 



