(iij4: Profetssor W. G. Adams [June 3, 



its pole vvliich attracts the marked end of our needle must lie at the 

 beginning of the disturbance to the east of Kew and Lisbon, to the 

 north of Vienna, and to the north-west of St. Petersburg ; the Lisbon 

 vertical force curve also shows it to be below the surface of the earth. 

 Hence an inductive action equivalent to a change of position of the 

 north magnetic pole towards the geographical pole would account for 

 these changes. The strengthening and weakening of a magnet with its 

 north pole to the north on the meridian of Vienna might possibly 

 account for the magnetic changes observed between 9 . 30 and 10 . 30 at 

 night, Greenwich time, on March 15, 1879. If we attempt to explain this 

 disturbance by currents of electricity or discharges of statical elec- 

 tricity in the air above the needles, then we must imagine that at first 

 there is a strong current from the south-west over St. Petersburg, 

 from the west over Vienna, and from the north-west over Kew and 

 Lisbon, tbe vertical force needle at Lisbon showing that the current 

 from tbe north-west lies somewhat to the east of Lisbon ; that at the 

 Mauritius this current is from the north, and at Bombay from the 

 south. 



Hence we must imagine that a current of electricity passes down 

 from the north-west to the south-east, going on towards the east over 

 Vienna and towards the north-east over St. Petersburg. This must 

 be kept up very much along the same line throughout the first part of 

 the disturbance, and then tbe current or currents must be altered in 

 strength in the same manner at all stations. 



We will next consider what would hardly be called a magnetic 

 storm, but a few very small deviations of the magnetic needle, lasting 

 from about 5 . 30 to 7 . 30 p.m. on March 26, 1879 (see Plate 2). Only 

 the comparison of the originals will give the closeness of the 

 similarity of the curves, and the cuiwes for Vienna and Kew are 

 coincident. 



When the declination needle is deflected to the west, the horizontal 

 force needle is deflected with its marked end towards the south, so 

 that in this disturbance the two needles are drawn towards the south- 

 west at the same time with greater or less power, and twelve similar 

 curves are clearly traced out in the Vienna and Kew curves during 

 the two hours. From the remarkable similarity in these disturbances 

 and their occurrence at the same time, we should expect that the cause 

 of disturbance is so far removed from the places of observation that 

 the difference of tbeir distances from it need not be considered. This 

 might not unreasonably be urged as an argument in support of a 

 tlieory that such disturbances are due directly to the action of the 

 sun regarded as a magnetic body. These disturbances are all so 

 very small, that but for the comparison of photograpbs they would 

 probably be lost sight of, yet we see that the same deflections occur 

 at the same instant at Kew and at Vienna, at St. Petersburg and at 

 Melbourne. The numerical comparisons of observations made every 

 five minutes on certain days previously fixed upon would jirobably 

 never have shown the way in which these minute changes of magnetic 



