52 REPORT—1858. 
in July; in the southern the minimum is more suddenly arrived at, and as 
suddenly abandoned, andjit extends over less than one month. 
If we take May and June as one minimum in the northern, we have 
a second but very much lower one in September, and the corresponding 
second minimum for the southern hemisphere in August. 
The annual paroxysmal maximum for the northern hemisphere is di- 
stinctly in January, and for the southern in November. 
January and March are second maxima in the southern, as August and 
October are in the northern. 
Whatever be the irregularities month by month however, the prepon- 
derance of seismic paroxysm for the whole twelve months lies amongst those 
that form the winter of our northern hemisphere. 
In Plate IX. figs. 1 to 6, curves are drawn for mensual energy, for several 
corresponding periods for the northern and southern hemispheres. Figs. 1 
and 2 indicate these for the whole period before, and for sixteen centuries 
after the commencement of our era. Here the northern minimum falls 
in July, and a second minimum in October, while the southern mini- 
mum falls in April, and the second before September, approximating thus 
to accordance with the curves of the whole catalogue, but less “ prononcées.” 
Then for later but shorter observed periods, figs. 3 and 4 give the mensual 
energy for a.p.1700 to 1800, and figs. 5 and 6 for a.p. 1800 to 1850, being 
the half century in which, for convenience of comparison, the ordinate of 
time is double the scale of the other figures, the whole twelve months being 
represented by an ordinate of equal length in all. 
In the eighteenth century, then, we find in the northern hemisphere the 
minima less distinct, occurring in July aud September, and the maximum in 
January, with a second maximum between October and January ; and in the 
southern hemisphere, the minima about March and September, and the 
maxima in May and December. 
Again, in the first half of this nineteenth century we have (fig. 5) the 
northern minimum in June, a second but less marked minimum between 
November and December, and the maximum again in January and Fe- 
bruary; while in the southern hemisphere we have (fig. 6) the seismic 
minimum in March, and a second but much less marked one between July 
aud August, and the maximum in November, with feeble indications of a 
second slight one in June. 
Such are, then, the results of our monthly discussion. Comparing both 
hemispheres, they show several points of general agreement, and some of 
decided want of accordance. Little comparative weight can be ascribed to 
the few observations as yet made in the southern hemisphere, where so large 
a proportion of the earth’s surface is covered by the ocean, and where so 
little of the land has, until a very late date, been the subject of observational 
record at all. It would seem warrantable therefore not to permit any such 
unaccordant phenomena between the two hemispheres to obscure the strong 
presumption which the facts otherwise support, that there really is a seismic 
paroxysm in the months forming the end and commencement of the civil 
year. It may not havea natural or cosmical basis, it may possibly be one of 
the accidents inseparable from an observational catalogue; but both this 
extended catalogue, and nearly all the partial catalogues of others, indicate — 
it as a fact, and one not absolutely without some extraneous support in the 
present state cf our knowledge. 
When we group the consecutive months into four seasons, spring, summer, 
autumn, and winter, and reproduce the curve of seismic energy for the whole 
year, and separately for each hemisphere and for the whole period of the 
