SCIENCE. 
193 
other hand, no such flood as deposited this gravel has ever 
occurred within the historical epoch. No such large bould- 
ers are ever now carried down the river. No modern rain- 
storms could cause such a flood. It is difficult to assign 
any other cause than that of a melting glacier. Yet such a 
glacier could hardly be the great Northern glacier, for these 
gravels are much newer than those of the Champlain epoch. 
There is here evidence of a second and more recent glacier 
in the Delaware valley. 
The hypothesis of a second glacial epoch seems to explain 
all the facts observed. A similar period in Europe — the 
reindeer period — is supported by many facts. Should such 
a period not be traced in America, the date of the melting 
glacier must be made much more recent than that generally 
assigned. 
The relics of man which occur in the Trenton gravel, 
and which were first found by Dr. C. C. Abbott, are of 
great interest. In shape, in size, in workmanship, and in 
material the implements here found are quite different from 
those used by the Red Indian. These “ palaeoliths ” are 
imbedded at various depths in undisturbed Trenton gravel. 
There are two points which offer strong evidence that the}' are 
as old as the gravel. The first is the fact that modern Indian 
implements (“ neoliths ”), although abundant on the sur- 
face, never occur more than a few inches below it, and are 
never associated with the palajoliths, which are found at 
depths of from five to forty feet below the surface. This 
fact alone argues a different age for the two classes of im- 
plements. The second fact is that, when found below the 
surface, the palseoliths always occur in the Trenton gravel 
and never in older gravels. The writer has gone over, with 
Dr. Abbott, much of the ground where the implements 
occur, and it was very interesting to find that it was only 
within the limits of the Trenton gravel, previously traced 
out by the writer, that Dr. Abbot had found implements I 
below the surface. Here, then, is the strongest probability, 
even if the implements were found on the surface only, 
that they belonged to and were of co-eval deposition with 
the river gravel. 
The implements found in the river gravels of Europe are 
of similar type, though as a rule perhaps less rude. It is 
of interest to find that very similar implements have been 
used by the Eskimos, and it is probable that that race, now 
living in a climate and under conditions perhaps similar to 
those once existing in the Delaware, may have some kinship 
with the pre-Indian people of this river. The occurrence 
of bones of arctic animals in the Trenton gravel indicates 
a period of cold. 
All the evidence now gathered points to the fact that at 
the time of the Trenton gravel flood, man, in a rude state, 
lived upon the ancient banks of the Delaware. If future 
archaeological work can show a connection between this 
people and the Eskimos, it may be appropriate to call the 
period of the Trenton gravel and of this palaeolithic people 
— a period perhaps following a second glacial age — the 
Eskimo period, a name more suggestive, and derived from a 
higher order of beings than that which gave the name 
“ Reindeer Period.” 
While others have held that the occurrence of imple- 
ments in the Trenton gravel indicates the existence of man 
in inter-glacial or even pre-glacial times, the writer believes 
that the investigations here described indicate the origin of 
man, at a time which geologically considered, is recent. 
Neither in the Champlain deposits, in the morainic material 
of the north, or in any older gravels have undoubted traces 
of man been discovered. 
The actual age of the Trenton gravel, and the consequent 
antiquity of man in the Delaware, cannot be determined by 
geological data alone. It is the aim of this paper to define 
man’s antiquity in relation to geological rather than to his- 
torical events. If, in showing that the Eskimo period is 
the last of the geological ages, it does not necessarily fol- 
low that it is by any means recent ; it must be remembered, 
on the other hand, that its high antiquity is not proven by | 
the facts thus far observed. 
The conclusions to which the facts seem to point are 
briefly summarized as follows : 
r. That the Trenton gravel, the only gravel in which im- 
plements occur, is a true river deposit of post-glacial age, 
and the most recent of all the gravels of the Delaware 
valley. 
2. That the palaeoliths found in it really belong to and 
are a part of the gravel, and that they indicate the existence 
of man in a rude state at a time when the flooded river 
flowed on top of this gravel. 
3. That the data obtained does not necessarily prove, 
geologically considered, a vast antiquity of man in Eastern 
America. 
PYROLOGY, AND MICROSCOPICAL CHEM- 
ISTRY. 
By W. A. Ross, Lt. Colonel, late R. A. 
(1) . In the year 1869, at Simla, India, having applied a 
trace of oxide of cobalt to a bead of boric acid before the 
blowpipe, I observed that, instead of dissolving, as I had 
been led to expect, small round black spots were formed, 
which, appearing perfectly round through the clear bead 
from every point of view, seemed to be spherides or balls. 
It was afterwards found that 14 oxides form such balls in 
boric acid, B. B., among which the most useful pyrological 
was that of calcium. 
(2) . I found, by the average of five assays, that the weight 
of the calcium borate ball, extracted by boiling water in 
which it is utterly insoluble, while the containing bead is 
rapidly dissolved — was a constant multiple of the weight of 
the calcined lime taken to make it, and that this multiple 
was 4.5. Thus, if w = the weight of the ball, the formula 
~ represented the quantity of pure lime in it. If calcium 
hydrate was taken, instead of calcined lime, a clear ball 
was still formed within the bead, which latter became 
opaque through opalescence, and as the balance showed 
that this ball also contained the above mentioned propor- 
tion of calcined lime, the opalescence was attributed to 
chemical water. 
(3) . Circumstances of a painful nature, which I need not 
here relate, prevented my going further into this matter for 
eight years, but I vainly solicited the Microscopical Society 
to take it up, and having been enabled this year (about two 
months ago) to purchase a binocular microscope, with 
polariscopic apparatus attached, I fitted a small spectro- 
scope I had by me into one of its eye-pieces with cotton 
wool, etc., and renewed my examination of these boric 
acid balls. 
(4). Notwithstanding the undoubtedly chemical nature of 
the combination I have called “a calcium borate ball,” the 
phenomenon of ball formation itself is obviously as much 
related to the subject of molecular physics as to chemistry, 
and seems explainable briefly as follows : All liquids 
| having cohesion have, under circumstances of equilibrium, 
