218 
ME. C. V. WALKEE ON MAGNETIC CALMS AND EAETH-CUEEENTS. 
the passage of a powerful current ; and all with the same negative result. An observa- 
tion is made, say on the Tonbridge-London line, and the deflection noted. A powerful 
current from the ordinary telegraph battery (a current which it would be imprudent to 
receive on the observing galvanometer) is transmitted for a given time, say half a minute, 
through the Tonbridge-London circuit, in the direction which would have produced 
the deflection previously observed. After this the observation is repeated. No appre- 
ciable difference has in any instance been found in the deflection. The direction remains 
the same ; and the value unaltered. So that the currents, as far as the polarizing of the 
plates is concerned, may be regarded as true and proper earth-currents. 
The alterations in direction of the currents and the varying values in either du’ection 
indicate that they are in nowise due to the mere electromotive force of the earth-plates 
employed. 
I have mentioned in my former communication (pp. 94, 95) that the connexion with 
the earth is very frequently made by means of the fish-jointed rails. Some misghings 
might arise on a first glance as to the influence of this arrangement over the results. 
The ciuTent collected under such circumstances, however, would be true in dmection, but 
reduced in value. We need not enter into the discussion of this question from the fact 
that no such earth-connexion has been required for our present purposes. 
To prevent misapprehension, I have thought it better to give a list of the earth-con- 
nexion employed at all the stations concerned in this investigation. 
London Gas-pipes ; and a lightning conductor terminating in a wet 
pit of coke. 
Tonbridge Gas- and water-pipes. 
Hastings Gas- and water-pipes. 
Eamsgate Harbour . . . Water-pipes. 
Dover Gas-pipes. 
I still continue taking observations ; but they are all of the same character as those 
now placed on record, and merely afford further illustrations of the points that have 
been discussed. It would be premature to say that the subject is tolerably exhausted, 
as far as the means at my command are concerned ; but I do not at this moment see 
any salient point that is within my reach. The steady daily and hourly march of these 
phenomena, and their relation, if any, to the like march of magnetometers, will soon be 
within the reach of Mr. Aiky ; and we may be well assured that these and the other 
collateral questions will be ably discussed by him. 
The results arrived at in these two communications may be briefly summed up as 
follows : — 
1st. That currents of electricity are at all times moving in definite directions in the 
earth. 
2nd. That their direction is not determined by local causes. 
3rd. That there is no apparent difference, except in degree, between the currents 
