368 Transactions—Geology. 
The greatest influence of the sun and moon occurs on the days of half 
moon, but fracture would most likely take place somewhat later. The 
weeks following the days of half moon may be considered those on which 
the majority of great eruptions would take place. 
I have only been able to ascertain the exact days on which 27 of these 
have been recorded—the earliest being the eruption of Monte Nuova, which 
occurred on the 29th September, 1538, and the latest that which took 
place in Iceland on the 11th June, 1878. Calculating the moon’s age for 
the day on which each eruption occurred, I find that 61 per cent. are 
favourable to the hypothesis, and 39 per cent. unfavourable. 
There have been 284 days since 1868, inclusive, on which shocks of 
earthquake have been felt in New Zealand—nearly all very slight. I 
cannot say the result is very favourable, as the number of those which 
occurred during the weeks following, exceed those during the weeks pre- 
ceding half moon by only 8 per cent. 
The total number of shocks contained in this analysis is far too small 
to be of any importance. As far as it goes, it is not unfavourable ; indeed, 
the proportion of great eruptions which occurred during these weeks is 
very much greater than would be looked for. 
It would, however, require a complete analysis of many thousands of 
shocks before it could be stated with any confidence that the result was 
favourable or the reverse. 
It is, of course, the purest speculation to endeavour to estimate the 
per centage of influence which the tides would have ; but they must have 
some influence if my hypothesis is correct. 
I now leave my hypothesis in the hands of the members of the Society 
for their criticism. I believe it explains most of the facts which have been 
recorded by observers better than any of the theories generally received ; at 
least it does away with a great deal of unscientific world making in which 
volcanologists are too fond of indulging. The only essential suppositions E 
haye made which are not supported by experiment or the clearest inference, 
are that the earth owes its interior heat to condensation, and has lost by 
radiation not more than 49 parts out of every 50 of the heat acquired by 
the compression it has undergone, since its average specific gravity was 
equal to that of the surface rocks. These suppositions are not at variance 
with the Condensation Theory, by which Helmholz has calculated that the 
solar system has lost 453 parts out of every 454 it had when condensation 
began.* 
*I also assume that the inner parts of the Earth are not very dissimilar from the 
outer part which we are acquainted with. The theory of a great inner heat requires that 
we must suppose the centre of the Earth to be formed of molten gold, or of some other 
tance of at least equal specific guite's Such startling theories can only be accepted 
when proved by the clearest evidence 
