113 
of Edinburgh^ Session 1862-63. 
In the first of these classes a law of hours was manifestly ob- 
served, the values of the earth-currents for the hours of the night 
being extremely small. But in the second, and especially in the 
third class, the law of hours was observed to fail ; and in the latter 
of these classes the peculiar action of disturbances was very mani- 
fest, the tendency of such disturbances being to create very strong 
earth-currents at the moment of their occurrence ; and it is notice- 
able that these earth- currents were as often positive as negative. 
It was remarked by the author, that the very great strength of 
those earth-currents, which take place at the moments of disturb- 
ance, is in favour of the theory of induction, since the peculiarity 
of a disturbance is not so much a very great as a very rapid and 
abrupt departure of the magnet from the normal position ; and 
since, on the theory of induction, the corresponding earth- current 
will be due to abruptness of magnetic change, we thus obtain an 
explanation why the currents which accompany disturbances are so 
very powerful, and also why these are as often positive as negative. 
With regard to the first class of earth-current observations, or 
those which occurred during magnetic calm, the author believed 
the daily range indicated by these observations to be the induction 
effect of the daily magnetic change, on which hypothesis the small 
value of the currents for the night hours might he accounted for 
by the corresponding fact that during these hours the magnetic 
change is exceedingly small. 
4. Note on a Pictish Inscription in the Churchyard of 
St Yigeans. By Professor Simpson. 
Dr Simpson considered the inscription to be “ Drosten, Son of 
Voret, of the family of Fergus.” 
5. On some Kinematical and Dynamical Theorems. By 
Professor W. Thomson. (Abstract by Professor Tait.) 
In the course of investigations which the author had been led to 
make in connection with a Treatise on Natural Philosophy which 
he and Professor Tait are about to publish, he met with some 
remarkable theorems, which appear to be new and of considerable 
