64 REPORT — 1875. 



by the pressure of other duties. The Committee, if reappointed, propose not 

 only to complete the reduction of the present observations (which work is 

 already in progress), but to extend the investigation so as to include a well- 

 deiined series of sulphur compounds (a number of which have been already 

 prepared and some partially investigated), with the view of repeating the 

 observations on the relation of the specific volume of sulphur to the manner 

 in which it is held in union. These results will also afford material for 

 discussing Buff's hypothesis, that the specific volume of an element varies 

 with its atom-fixing power. The only hydrocarbons we have hitherto in- 

 vestigated are ethyl amyl and heptane, both C^ Hj,,, concerning which there 

 is proof that, contrary to Kopp's law, their specific volumes are not iden- 

 tical. Should this result be confirmed by the examination of similarly 

 related hydrocarbons, the statement concerning the invariability of the 

 specific volumes of carbon and hydrogen will need modification. 



Sixth Report on Barthquakes in Scotland, draivn up by Dr. Bryce, 

 F.O.S. The Committee consists of Dr. Bryce, F.R.S.E., Sir W. 

 Thomson, F.R.S., J. Brough, G. Forbes, F.R.S.E., D. Milne- 

 Holme/ F.JS./S.S., and J. Thomson. 



Dttring the year that has elapsed since the last Meeting of the Association 

 the Comrie district has been in a state of entire quiescence, and no earth- 

 quake has been reported from any other part of Scotland. Your Committee 

 has thus nothing of general interest to lay before the Meeting this year. 



The plea put forward at the last Meeting for an increase of the grant was 

 founded on the necessity felt by the Committee of having additional appa- 

 ratus set up at Comrie. They desired to have a check of some kind on the 

 indications of the seismometer belonging to the Association, which is placed 

 in the tower of the parish church, as well as additional means of testing both 

 the direction and intensity of the shocks. Por this purpose it seemed neces- 

 sary to have apparatus of a different kind, and to find a locality somewhat 

 distant from the spot where the seismometer now stands. After experimental 

 trial had been made of contrivances of various kinds, the method of upright 

 cylinders (one of those recommended by Mr. Mallet in his paper in the 

 * Admiralty Manual ') was adopted. The difiiculty of finding a suitable site 

 and a competent observer, to whom it should be a matter of perfect conveni- 

 ence to visit that site, next presented itself. No suitable apartment in which 

 to set up the cylinders could be found in the village ; and the Committee 

 therefore resolved to erect a small building for the special purpose. Their 

 wish being made known to Peter Drummond, Esq., who resides on his own 

 property of Dunearn, about half a mile direct distance from the parish cliurch, 

 and nearer to the supposed earthquake-focus, he most kindly offered a site 

 on the grounds surrounding his house. Here, accordingly, on a spot care- 

 fully selected, the building has been erected. It is founded upon a rock, 

 the same slate-rock of which the valley westwards to Loch Earn and the 

 enclosing hills are composed, and in continuity with it ; while it is completely 

 sheltered from the agitating influences of all winds ; so strongly built, indeed, 

 is it, that, even if the situation were exposed, only a storm of extreme violence 

 could produce any disturbing effect. No one can have access to the building 



