of Edinburgh , Session 1880-81. 
187 
13. That of twenty-two lighthouse observers between Cape Wrath 
and the Mull of Galloway, who were situated on the older formations 
(Laurentian, Cambrian, and Metamorphosed Lower Silurian), eleven 
felt the shock, whilst of thirteen observers situated on newer rocks, 
it made itself known only to two of them ; and that the earthquake 
was therefore more generally felt on the older rocks of Scotland. 
14. That stations situated near one another, and on the same 
formation, did not necessarily both receive the shock, and that faults 
or trap dykes did not seem to affect the passage or intensity of the 
wave in any way. 
15. That the observations of time at Armagh, Belfast, and Omagh, 
show that the shocks at these places were most probably propagated 
direct from Phladda in Scotland, and that the severity of the shock, 
and the “ rumbling ” noises heard in and around Leterkenny, were 
probably due to a second and local source of disturbance, generated 
by the arrival of the shock from Phladda. 
2. On the Classification of Statistics. Part I. 
By Mr P. Geddes. 
3. On Professor Cayley’s Theorem regarding a Bordered Skew 
Determinant. By Mr Thomas Muir, M.A. 
(This paper is to be found in the Quarterly Journal of Mathematics, 
vol. xviii.). 
4. The Law of Extensible Minors in Determinants. 
By Mr Thomas Muir, M.A. 
5 . Additional Note on a Problem of Arrangement. 
By Mr Thomas Muir, M.A. 
1. The present note is a continuation of a short paper which ap- 
peared in the Proceedings of the Royal Society of Edinburgh for 
session 1876-77. The problem in question is that referred to in 
Professor Tait’s “ Memoir on Knots,” viz. : — To find the number of 
possible arrangements of a set of n things , subject to the conditions 
that the first be not in the last or first place , the second not in the 
