510 The Astronomer Royal on a recent Magnetic Disturbance- 



between 59 d and 61 d , till 3 h ll m , the scale then reading 59 d, 7. 

 The disturbances now became as surprising as those with the 

 other needles ; a steady and rapid increase of scale-reading 

 took place, with a strange jerking motion. 



h m s d 



At 3 14 48 p.m., Gottingen mean time, the scale read 61*4 



21 3 ... ... 61-2 



27 26 ... ... 64-2 



28 6 ... ... 64-4 



28 46 ... ... 64-8 



38 16 ... ... 73-6 



38 56 ... ... 73-2 



Then there was a remarkable start to 78 d *0 ; and here it 



remained stationary from 3 h 39 m to 3 h 43 m , when it started 

 back. 



h m s d 



At 3 47 41 p.m., Gottingen mean time, the scale read 69*9 



56 31 ... ... 65-6 



4 51 ... ... 63-7 



8 55 ... ... 63-1 



15 11 ... ... 646 



47 41 ... ... 61-4 



Then the reading increased a little, and then gradually 

 decreased, till 5 h 53 m 12 s p.m., Gottingen mean time, when 

 it read 57 d, 8 ; it then increased to 6 h 16 m 12 s , when the scale 

 read 62 d -l. 



It^then oscillated between 58 d and 60 d , until 7 h 25 m 13 s , 

 when a sharp diminution to 53 d, 9 took place. The readings 

 alternately increased and decreased for the next six hours, 

 oscillating all the time between 53 d and 57 d . 



From the preceding account it will be seen, that the mag- 

 netometers were more affected on this day than ever before, 

 and that the great disturbance affected the three instruments 

 at the same time. 



The most abrupt and violent fluctuations of the meridian 

 needle occurred between 3 h 36 m and 3 h 46 m . At 3 h 35 m 21 s 

 the vertical-force magnet went beyond the scale ; at 3 h 45 m it 

 again came on. The horizontal-force needle began its great 

 deflexion before 3 h 38 m 16 s ; it was over at 3 h 48 m ; and, 

 probably, had there been an observer at each instrument, it 

 would have been found that the effects on all were simultane- 

 ous. Such was Mr. Glaisher's impression while observing ; 

 but (as he remarks) the startling and bewildering effect of so 

 great changes was such, that all that he could do was to make 

 such observations as seemed practicable, with a view of dis- 

 covering the extent of such extraordinary disturbances. 



