FLINT IMPLEMENTS FOUND IN KENT’S CAVERN. 369 
Stalagmite and the underlying Breccia of Kent’s Hole—deposits 
necessarily vastly older than the most ancient in which human 
relics had then been found—were not at that time discovered or 
even suspected. 
Whilst, however, Science modestly declines to say how many 
times the earth has rotated on its axis, or revolved round the sun, 
or how often the pole of the equator has travelled round the pole 
of the ecliptic since the fragments of red grit were carried into 
Kent’s Cavern, it is, perhaps, possible to throw in a few stepping 
stones enabling us in imagination to cross, step by step, the stream 
of time which separates us from the earliest known men of Devon, 
- and to form a more adequate notion of its breadth than would be 
attainable by looking at it in its entirety. 
There are five lines of enquiry, or five kinds of evidence, which 
may be here considered. First, the Cavern deposits, or the G‘eolo- 
gical evidence; secondly, the animal remains found in them, or the 
Paleontological evidence ; thirdly, the human industrial relics which 
have been exhumed, or the Archeological evidence; fourthly, the 
changes in the configuration of the surface of the district adjacent 
to the Cavern, and, still more important perhaps, the alterations 
that have taken place in the relation of Britain to the Continent, 
or the Geographical evidence; and, fifthly, the thermal changes, 
or the Climatological evidence. It would be absurd to attempt a full 
discussion of even one of those topics on this occasion, and the 
time at my disposal forbids me to do more than to make a few 
general observations. 
Archeologists have found it convenient and possible to divide all 
human time as represented in Western Europe into certain distinct 
Ages, of which that in which we live, or the first, if it is allowable 
to read History backwards, is the Lron Age. Taking the labours 
and discoveries of archeologists as our guide, there was an early 
time when Iron was not used, but men fashioned their most power- 
ful tools in the compound metal called Bronze—a mixture of copper 
and tin in definite proportions—and the period thus characterized 
is denominated the Bronze Age. Proceeding thence to a more 
remote antiquity, a time is reached when metals seem to have been 
entirely unknown, and the most efficient tools were made of hard 
stones, chiefly flint and chert, which were generally elaborated with 
great care, and finished by polishing. In still more ancient times, 
