Editorial Comment. 421 
lined a geological chronology of the period on zoological data. 
The professor concluded by pointing out the continuity of the 
series, and objecting to tbe exclusion of the historic period from 
the domain of geology, adding a short summary of the relation 
of man to the ice age, and alluding to the difficulty, at present, 
of expressing geological time in chronological terms, because 
of our ignorance of the rate of action of the various causes. ''We 
may," he said, "draw cheques on the bank of Force, as well as on 
the bank of Time." 
Several papers were read on the secondary, especially the Juras- 
sic rocks of England. This subject has, of late, obtained special 
attention in consequence of the hope which has been indulged 
that water might be found in some of the lower beds sufficient to 
aid in supplying the metropolis. Thus far the reward, though 
substantial, has not come up to the expectative, but there is rea- 
sonable ground for anticipating useful, if not abundant, supplies. 
Borings also, some of them yielding cores 12 inches in diameter, 
have been made to prove the existence of palaeozoic rock at no 
very great depth below London. The hope is still entertained 
that workable seams of coal may in this way be found in the 
south-east of England, as such seams were found by the French 
government by similar borings in the north of that country. 
Dr. Persif or Frazer followed with a paper, in which he advocated 
the Archaean nature of the rocks found in the nucleal ranges of 
the Antilles. During a visit this year to the south-eastern part 
of the island of Cuba, the speaker had made some examinations 
of the rocks which form the nucleus of the spurs of the Sierra 
Maestra, and there is strong reason to believe of the axial range 
of the entire island and of Jamaica, Santo Domingo, Puerto 
Rico, and the Windward islands as well. From the field ob- 
servations there made, and an examination of the specimens 
under the microscope, it seems highly probable that these rocks, 
instead of being igneous extrusions of the Tertiary period and 
later, are in reality of much earlier date, and may not be entirely 
volcanic. Several considerations support this view. Microscopic 
analysis shows immense alteration to have taken place, and, con- 
sequently, a very long period to have elapsed. The complexity of 
the congeries of rocks forbids the hypothesis of their having 
been derived from one mass. Where this congeries, therefore, 
is unconformably adjacent to the Tertiary, there can be no rea- 
