OBSERVED IN THE WIRES OF THE ELECTRIC TELEGRAPH. 
69 
precisely the same character as those described in the foregoing part of this paper, 
were found to take place on the short telegraph from the Electric Telegraph office in 
the Strand to the Nine Elms Station, the wires of which are laid underground in 
tubes throughout their length. 
Taking this fact in connection with those before mentioned, viz. that no deflection 
is produced in a wire suspended throughout its length in the air, that no deflection 
is produced with a wire having only one earth connection, but that in every case 
deflections are exhibited in a vdre having two earth connections, and that the direc- 
tion of the current in the wire at any given time is dependent on the relative positions 
of the earth connections, the most probable explanation appears to be that the cur- 
rents are terrestrial, of which a portion is conveyed along the wire, and rendered 
visible by the multiplying action of the coil of the galvanometer. 
POSTSCRIPT. 
{Copy.) 
My dear Sir, Derby, May 8, 1848. 
It has often occurred to me, that if the deflections were caused by atmospheric 
electricity, they should occur before and during storms. I have never observed this 
to have been the case ; the needles are seldom moved by lightning, and if they are, 
it is in spasmodic twitchings, perfectly different to the most rapidly varying deflec- 
tions ; but the bells are generally rung if a storm occur at any point of their circuit; 
on the other hand, deflections, unless exceedingly powerful, do not ring the bells. 
A marked difference is always observed in the effect on the bells, between light- 
ning and deflections, the first causing them to ring only a second, the last for several 
minutes. 
I have twice this winter foretold an aurora ; the connection between this pheno- 
menon and the deflections is indisputable. 
In the great storm at Leeds, Huddersfield, and the neighbourhood, of a few Sun- 
days since, I had four pair of needles demagnetised at Normanton, one at Skipton, 
and a discharge between the points of the conductors at Bradford. The wires were 
disconnected from the instruments for safety, and a discharge took place from the 
free ends ; still the needles were not deflected in the least degree, either before or 
after the storm, nor at any time when the instruments were in circuit during its 
continuance. 
I had an excellent opportunity at Normanton last Monday of testing the direction 
of the line of “ no-action.” 
The Manchester and the Derby instruments were each strongly deflected. I opened 
the circuit on one needle from Manchester to Derby, leaving the other needles on 
