Tvn?. C. V. WALKEE ON MAGNETIC STOEMS AND EAETH-CUEEENTS, 105 
current must have been very strong, seeing that the action >vas so great in both of the 
extreme groups, although their bearings with each other made an angle of no less than 
138°, that the galvanometer needles in each case were described as being “hard over.” 
In the later entries, which were of observations made subsequently to the erection of 
the graduated galvanometer at Eamsgate, the values are entered in degrees. If a query 
(1) occurs, it implies that the observation was made and the direction given, but the 
value was not noted. When blanks occur in the Table, it means that no observation 
was made on the group against which the blank appears, at the time in question. In 
all cases where simultaneous observations have been made, the direction of currents 
in intermediate groups is in strict conformity vdth the results obtained from the two 
extremes. And when the dhection changes, as in Table XII. section 2, for one extreme, 
it changes also for the other, and for all the intermediate groups that are the subject of 
observation. The remarks, therefore, which have been made on section 1 are, mutatis 
mutandis, equally applicable to section 2. Simultaneous observations have now and then 
reached me from the Minster — Deal group. No. 19. I have entered cases, but pass them 
over here. They take 4° from the range, reducing it to 38° in the instances given. 
The case shown in fig. 5 is the most complete ; it has not attracted attention so fre- 
quently as the last. The telegraph group No. 23, London — Tonbridge, is less sensitive, is 
more liable to interruption and not so convenient for observations, and it is more distant 
from the centre of action. The observations on this group have a special interest of their 
own. There are two lines of telegraph between Tonbridge and London ; one is 40^ 
miles in length, and goes via Eed Hill; the other is 57|- miles in length, and takes a 
circuitous route by Paddock Wood, Maidstone, Strood, Gravesend, and Woolwich. The 
currents in these two groups in all instances coincide, and have reference to the bear- 
ings London — Tonbridge, and not to the route. This is the more striking because one 
wire, as may be seen by the Map, comes to Tonbridge from the eastward and the other 
from the westward, and the currents, as far as the wires are concerned, arrive from 
directly opposite points of the compass, and to all outward appearance are opposed to 
each other. 
The bearing of No. 23, the London — Tonbridge group, is 13° W. of N. By treating 
these bearings as before, we have 
No. 26 . . . 90 — 44=46 E. of N. ; the northern limit. 
No. 23 . , . 90 — 13 = 77 E. of N. ; the southern limit. 
31 ; the total range. 
The 3rd and 4th sections of Table XII. contain cases in point, each, as in sections 1 
and 2, being the converse of the other. All the observations in these sections confirm 
those in the other two, with the advantage of having 1 1° more of azimuth, and reducing 
the range within which the true direction is to be sought, to 31°. By referring to fig. 1, 
it will be seen that between Nos. 23 and 25 there is a blank space which amounts to 
31°. Had we possessed telegraph lines having azimuths that might fall within the 
AIDCCCLXI. Q 
