60 REPORT—1850. 
pyrites of the latter, and the strange mixture of pyrites and vegetable matter, 
which Mitscherlich describes as used in Saxony for making copperas from, 
and which only needs to be dug out and moistened to heat and decompose 
spontaneously, would give rise to black and fcetid water, saturated with 
sulphates, evolving torrents of sulphuretted hydrogen and carbonic acid, and 
mingled with red mud of oxides of iron! Again, should such crevasses 
affect a country such as that of the salt formation of Cheshire, and stretch 
also into some of the neighbouring coal-measures, what rapid and important 
chemical action would result from all the above, brought into contact with | 
saturated solutions of common salt, with gypsum, with limestone and with 
clays dissolving into a paste at the first approach of moisture ! What enormous 
evolutions also of carburetted hydrogen from the coal-beds would the sudden 
relief of superincumbent pressure give vent to! 
Before proceeding to another branch of our subject, it will be proper here 
just to notice some few wnusual and ill-ascertained phenomena, of which the 
facts are doubtful or incomplete, and for which no perfect explanation can 
be offered :— 
Ist. Fixed objects are said in a few instances to have been inverted; thus 
by the “ sbalzo” or leap into the air, fixed pavement is affirmed by the 
Neapolitan academicians to have been thrown upwards, and found after- 
wards in its own place, but with the stones inverted. 
2nd. In the midst of the universal ruin and prostration of a whole town or 
village, a single edifice, and often one not remarkable for strength or 
for humility, has stood quite uninjured. Thus at Radicina, in Calabria, 
a single small square house of one story remained standing, all the rest 
of the town being prostrated ; similar events have been noticed in South 
America, where— 
3rd. “ Nodal points or lines” occur, namely, isolated portions of country 
which constantly escape the shocks which convulse the parts all round 
them ; these portions are so well known, Humboldt says, that the Peru- 
vians say “the rocks form a bridge,” “rocas que hacen puente” in 
Spanish. 
4th. Shocks felt in deep mines, as in the Marienberg in the Saxon Erzge- 
birge, not felt at all at the surface, and é converso, shocks at the surface 
not felt at all underground, as at Fahlun and Presberg in Nov. 1823. 
It would be easy to speculate on the probable causes of such pheenomena, 
on the known grounds of reflexion, refraction and total reflexion of elastic 
waves at certain angles, but the facts themselves are too doubtful to make it 
at all useful. But we must leave this subject, fertile as it is in consequences, 
having, as I trust, developed the nature of secondary effects from the earth- 
wave itself, sufficiently for the purposes of this Report, and proceed to a few 
remarks upon the secondary consequences of the great sea-wave. 
7th. The great sea-wave, when it comes ashore, after the partht 
quake, produces all the effects on land οἷ, ἃ great debacle. 
It does not appear needful to enlarge much upon this, as everything re- 
mains to be done in the way of accurate collection of facts, of which we 
have very few, principally due to Mr. Darwin, to W. Parish (see Geol. Soc.) 
and to Virlet (Bull. de la Soc. Géol. de acti tom. iii. p. 103), who has re- 
corded some curious facts as to the effects of a great sea-wave that broke 
over Santorin and the island of Sikino, seven leagues off, after the earthquake 
of September 1650. 
Mr. Parish, in a memoir presented to the Geological Society of London in 
November 1835, has collected all the historical notices of great sea-waves 
