162

IX.

ON A PIECE OF CHALK. (A Lecture delivered to the Working Men of
Norwich, during the Meeting of the British Association, in 1868.
Subsequently published in _Macmillan's Magazine_) 192

X.

GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE. (The
Anniversary Address to the Geological Society for 1862) 223

XI.

GEOLOGICAL REFORM. (The Anniversary Address to the Geological
Society for 1869) 251

XII.

THE ORIGIN OF SPECIES. (The _Westminster Review_, April 1860) 280

XIII.

CRITICISMS ON "THE ORIGIN OF SPECIES." (The _Natural History
Review_, 1864) 328

XIV.

ON DESCARTES' "DISCOURSE TOUCHING THE METHOD OF USING ONE'S
REASON RIGHTLY AND OF SEEKING SCIENTIFIC TRUTH." (An Address to
the Cambridge Young Men's Christian Society, delivered on the
24th of March, 1870, and subsequently published in
_Macmillan's Magazine_) 351

LAY SERMONS, ADDRESSES, AND REVIEWS.

I.

ON THE ADVISABLENESS OF IMPROVING NATURAL KNOWLEDGE.

This time two hundred years ago--in the beginning of January,
1666--those of our forefathers who inhabited this great and ancient
city, took breath between the shocks of two fearful calamities, one not
quite past, although its fury had abated; the other to come.

Within a few yards of the very spot on which we are assembled, so the
tradition runs, that painful and deadly malady, the plague, appeared in
the latter months of 1664; and, though no new visitor, smote the people
of England, and especially of her capital, with a violence unknown
before, in the course of the following year. The hand of a master has
pictured what happened in those dismal months; and in that truest of
fictions, "The History of the Plague Year," Defoe shows death, with
every accompaniment of pain and terror, stalking through the narrow
streets of old London, and changing their busy hum into a silence broken
only by the wailing of the mourners of fifty thousand dead; by the woful
denunciations and mad prayers of fanatics; and by the madder yells of
despairing profligates.

But, about this time in 1666, the death-rate had sunk to nearly its
ordinary amount; a case of plague occurred only here and there, and the
richer citizens who had flown from the pest had returned to their
dwellings. The remnant of the people began to to