578 



February 13, 1862. 



Major-General SABINE, President, in the Chair. 

 The following communication was read : 



" On Magnetic Calms and Earth-Currents." By CHARLES V. 

 WALKER, Esq., F.R.S., F.R.A.S. &c. Received February 

 3, 1862. 



(Abstract.) 



The author uses the word "calm" in a negative sense, "not 

 storm", and states that very few notable earth -currents have 

 attracted attention since the date of his original communication to 

 the Royal Society, which was read on February 14, 1861. 



Referring to that communication, he calls attenti on to the London, 

 Tonbridge, and Dover-London lines of telegraph, making an angle 

 of direction with each other of 149, and by means of which a few 

 groups of observations were made, from which the prevailing di- 

 rection of earth-currents was determined to be approximately N.E. or 

 S.W. He wished to multiply these observations and to modify them, 

 which he was well able to do from the circumstance that the Dover 

 -London telegraph wires enter his own private offi ce at Tonbridge, 

 where, by means of the necessary apparatus, he is able at any mo- 

 ment, when the wires are not occupied by telegrams, to obtain pos- 

 session of the whole wire from end to end, Dover-London ; or either 

 section, London-Tonbridge, or Dover- Tonbridge, the two former 

 being the limiting lines, or those making the greatest available angle 

 with each other, and the last, which is intermediate, being useful in 

 confirmation of the observations made on the other two. 



The telegraph needles have been rarely affected of late, the earth- 

 currents which form the subject of the present communication being 

 feeble. In order to their examination it was therefore necessary to 

 prepare a delicate galvanometer, which is properly connected with the 

 telegraph wire, and furnished with the simplest possible apparatus 

 for bringing it into action whenever occasion serves. It is within 

 arm's length of the author when in his office. The pressing-down 

 of a spring allows any earth-current that may be present to enter 

 the galvanometer ; a brass plug, placed in holes 1, 2, and 3, gives 



