380 
on this subject. It had been ascertained that the Carrara 
marble is not only not a primary rock, but was not older than 
the oolite limestone of Yorkshire. It appears to have been 
originally an oolite which had become crystalised from the 
heat of lava, and from the effect of pressure. 
He then proceeded, at considerable length, to point out 
the effects of heat, electricity, magnetism, and crystallisation, 
in producing the conditions of the metamorphic rocks. 
Among other localities alluded to as shewing signs of such 
agencies, were Broomsgrove Lickey, in Worcestershire, the 
Carradoc sandstone in Wales, the High Force of Tweddale, 
the Cheesewring in Cornwall, &c. He pointed out the 
molecular action of these rocks, and the mode in which they 
sometimes assumed the shape of the columnar rocks, such as 
those at Fingal's Cave, and the Giant's Causeway, and 
clearly proved that the Logan stones, rocking stones, and 
many other remains existing in this country, which are 
generally supposed to be of Druidical origin, were really 
geological formations. 
Mr. W. S. Ward then read a Paper : — 
ON THE STRUCTURAL CHARACTER OF ROCK, AND OF MINERAL 
DEPOSITS, AS EFFECTED BY ELECTRICITY. COMMUNI- 
CATED BY ROBERT HUNT, ESQ., F.R.S., OF LONDON. 
An idea has long prevailed that many of our rock forma- 
tions and metalliferous veins bear evidence of the disposing 
power of electricity. The uniformity of conditions — repeated 
over widely spread areas — the recurrence of the same kind 
of phenomena, whenever similar sets of conditions present 
themselves, have indicated a set of constants in nature which 
it is important to examine. 
Our rock formations may be distinguished into three 
marked varieties : — Crystalline, such as granite, &c. ; Sede- 
mentary or Aggregative, as sandstones, &c. ; and Laminated, 
