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]\IE. C. V. WALKEE ON MAONETIC CALMS AND KARTH-CUEEENTS. 
marked as the others ; their values are equally large. They are expressed graphically 
in figs. 12 and 13. 
The references and letters are the same as in figs. 10 and 11. The lines of direction 
are not favourable for arriving at an approximate place for the resultant. We have to 
seek it within the large arc of 131°, which includes respectively the whole of the S.E. or 
N.W. quadrant. I have the command at Tonbridge of the RamsgateHarbour-Tonbridge 
line, to which I shall have occasion hereafter to refer. It corresponds nearly with the 
Shalford-Red Hill, 34 — 33 of Table XI. and Plate III. fig. I; it makes an angle with 
the magnetic meridian of 99°, reckoned eastward. Many observations on this line are 
given in Table XVI. column 3, and in all cases will be found to coincide in direction 
with those on the Tonbridge-Hover line. I have therefore been able to lay down this 
line in figs. 12 and 13. It is indicated by the letters RT', and by three semibarbs. It 
reduces the arc to 112°, which, however, is still large, and which I cannot further 
reduce by the means at my command. 
Since I wrote the note (1861, July) which appears in the ‘ Philosophical Transactions ’ 
for that year. Part I. p. 96, the Astronomer Royal has laid his proposition for erecting 
earth-current wires before the Board of Directors of the South-Eastern Railway, which 
has been referred to me ; and it is needless to say has had my favourable report. The 
Directors have entertained the proposition most cordially; and have approved of the 
erection of the wires at cost price, and conceded the right of way and maintenance on 
the payment for each of a nominal sum of a few shillings annually. 
The Green wich-Dartford wire will make an angle of about 60° W. of N. (magnetic), 
nearly coincident with my Tonbridge- Ashford, or with the Tonbridge-Dover line of the 
present communication. The Greenwich-Croydon wire will make an angle of about 
47° E. of N., or not far from the direction of my Ashford-Hastings line. By combining 
the wires at Greenwich, the Dartford-Croydon line may be obtained, which is 84° E. 
of N., or nearly my Ramsgate- Ashford direction. Treating these lines in the usual 
wa,y, we shall have an arc of 36° or 107°. The former will be between N. and N.E., and 
out of the range. The latter, which however is very large, will include the range. I 
look forward with great interest to the completion of these wires, in order that we may 
