405 
of Edinburgh, Session 1876-77. 
light at the time. There is do damage done to anything about 
the station so far as I can see.” Bar. 29 - 43 at 9 a.m. 
These observations are valuable because of their trustwortniness 
as coming from wholly independent observers, and because few 
more sensible earthquake shocks have, so far as X know, been ob- 
served in Scotland. It is also remarkable that they do not appear 
to have been felt at any other lighthouse stations, although there 
are several others in the immediate vicinity. A record of them 
may therefore be useful to those engaged in seismic investi- 
gations. 
3. Additional Remarks on Knots. By Professor Tait. 
The author, in laying before the Society a revised and condensed 
version of the various papers recently communicated by him, took 
occasion to make some additional remarks. Of these only one 
need be given here. He pointed out that another fundamental 
term is requisite besides those already used viz., Knots and Links. 
For three endless cords may be inseparably entangled with one 
another, or locked together, even if no one of them be knotted and 
no two interlinked. 
Monday, 4 tli June 1877. 
DAVID STEVENSON, Esq., C.E., Vice-President, 
in the Chair. 
The following Communications were read : — 
1. On the Structure and Relations of the Genus Holopus. 
By Sir C. Wyviile Thomson, F.R.S. 
(Abstract.) 
The “ Challenger ” Expedition had no opportunity of visiting 
Barbadoes, and this I regretted greatly, as Sir Rawson Rawson, 
who was at that time governor of the island, had paid great atten- 
tion to the marine fauna, and was anxious to introduce us to his 
fine collection, which included many specimens of the rare and 
