March 23, 1894. 
It has been inferred by some from these experiments 
that rivers can be relied upon to purify themselves or free 
themselves from disease-producing organisms by the na- 
tural flow of afew miles. I do not, however, think that 
this is a safe assumption. The difficulty in conducting 
such experiments is so great, andthe knowledge that we 
possess of the conditions of life for pathogenic bacteria 
in running water is so scanty, that we are not justified in 
considering that water can be thus purified. Moreover 
there are many observations which show that rivers are 
not so purified. 
Thus at Providence an epidemic of typhoid fever was 
traced to a very slight pollution. of a large and rather 
rapid stream three and a quarter miles above the intake 
of the city supply. 
The city of Philadelphia suffers continually from a high 
typhoid death rate, and this is due unquestionably to the 
pollution of the Schuylkill River by sewage, much of which . 
contamination takes place many miles above the intake. 
The Merrimac River is polluted by sewage at many 
points along its course, especially at the cities of Concord, 
Nashua, Lowell and Lawrence. Typhoid fever has for 
many years been exceedingly prevalent at Lowell and 
Lawrence, which take their water supply from the river, 
although Lowell is fourteen miles below Nashua and Law- 
rence nine miles further down than Lowell. Moreover, 
when Lowell has suffered from an exceptionally severe 
outbreak, Lawrence has had the same experience soon 
afterwards. Newburyport is seventeen miles below Law- 
rence and takes its water from springs, but two years ago, 
this supply being low, a pipe was extended into the Merri- 
mac, and soon after an epidemic of typhoid occurred. 
These failures in self-purification are very instructive 
from the fact that the river flows so many miles without 
being freed from disease germs, and secondly because the 
river is very large as compared to the amount of sewage 
which enters it. 
From theoretical and experimental considerations, and 
still more from the experiences first related, we must be- 
lieve that a river once infected with disease-producing 
bacteria undergoes only a moderate degree of self- 
purification. What there is, is because the bacteria 
either settle to the bottom or die. Complete subsidence 
probably cannot take place in a flowing river, and as from 
one to two weeks are required to destroy the vitality of 
certain kinds of pathogenic organisms it can be only very 
rarely that conditions necessary for entire purification are 
found. As sewage is always likely to contain disease- 
producing organisms it follows that a river which receives 
sewage should be considered unfit to serve as a public 
water supply. Certainly if in rare cases it may be safe 
so to use it, we are not yet able to predicate the neces- 
sary conditions. 
LETTERS TO THE EDITOR. 
4%, Correspondents are requested to be as brief as possible. 
in all cases required as a proof of good faith, 
The writer’s name is 
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‘The Editor will be glad to publish any queries consonant with the character of the 
journal. 
Paleolithic Pottery. 
As bearing upon the discussion about the so-called 
hiatus between palxolithic and neolithic times, Dr. Brin- 
ton has made astatement in his ‘* Notes on Anthropology ”’ 
(Secence, March 9, 1894), to which I must decidedly demur. 
He says, ‘‘All must now concede that paleolithic man 
made pottery, which was long denied him.’’ I suppose 
that Dr. Brinton relies for this statement mainly upon the 
authority of the Marquis de Nadaillac, in various works, 
SCTENEGE" - 
and especially in his ‘‘ Manners ai : 
historic Peoples,” p. 100. But that gentleman is a closet 
archeologist and not an explorer, and he bases his 
Opinion upon antecedent probability, and not upon per- 
sonal knowledge, citing certain authorities of at least 
questionable value. In the single instance in which he 
makes an assertion upon his own authority he is certainly 
wrong. After stating that ‘‘ Evans and Geikie in their 
turn assert the absence in England of paleeolithic pottery, 
and Sir J. Lubbock energetically maintains this opinion,” 
he adds in a note ‘‘ But what is the value of categorical 
assertions of this kind in presence of the fragments of 
pottery found at different levels in Kent’s Hole?” Now, 
as I have had occasion to say elsewhere, if this statement 
were correct, it might be regarded as settling the question, 
for never were investigations conducted more carefully 
and more scientifically than were those carried on for 
fourteen years by Mr. Pengelly, at Kent’s Hole, near 
Vorquay, on behalf of the British Association. ‘This is 
what he says in his report made to that body in 1873, 
p. 213: ‘‘ The men of the black mould had a great variety 
of bone instruments; they used spindle-whorls, and made 
pottery, and smelted and compounded metals. The older 
men of the cave earth made few bone tools; they used 
needles and probably stitched skins together; but they 
had neither spindle-whorls, nor pottery, nor metals.” 
There could not be a plainer assertion than this of the 
absence of pottery from the more ancient deposits in 
Kent’s Hole. 
So, too, Prof. Boyd Dawkins, whose researches in the 
bone-caves of England are known to men of science the 
world over, says in ‘‘ Early Man in Britain,” p. 209: 
““ There is no reason to suppose that the cave men used 
vessels of pottery, since no potsherds have been dis- 
covered in any of the refuse-heaps which have been care- 
fully explored in France, Germany, Switzerland and 
Britain. The round-bottomed vase from the Trou du 
Frontal, considered by M. Dupont to imply that the art 
of pottery was known at this time, is of the same fashion 
as those of the neolithic age from the pile dwellings of 
Switzerland, and probably belongs_to that age. Had 
the cave men been acquainted with the potter’s art, there 
is every reason to believe that traces of it would be 
abundant in every refuse-heap, as they were subsequently 
in those of all pottery-using peoples, a fragment of pottery 
or of burnt clay being as little liable to destruction as a 
fragment of bone or of antler.” 
It is upon these discoveries of M. Dupont that De 
Nadaillac rests his belief that in Belgium, at any rate, 
the cave men made arude pottery, while the mammoth 
and the cave bear were still their neighbors. But it is a 
fact that among the fragments of pottery discovered by 
Dupont in the Belgian caverns were some that had been 
made upon the potter’s wheel; and it is certainly remark- 
able that ‘‘the round-bottomed vase from the Trou du 
Frontal” was quietly withdrawn from the glass cases of 
the Brussels Museum (‘‘ Matériaux,” x., 332; Xvi., 124). 
Within the past ten years some discoveries made by 
M. Fraipont, and his co-laborers, in certain belgian 
caverns at Spy, Engis and Petit-Modone, have been sup- 
posed by some persons to lend confirmation to Dupont’s 
views. But the thorough discussion of these finds by 
M. Cartailhac in ‘‘ Matériaux,” xxil., 63-78, shows upon 
how slight a foundation they are based. ‘The most they 
can be held to establish, if they are proved, is that during 
the age of the mammoth, pottery was invented by one 
tribe of savage hunters, living in Belgium; that the 
knowledge of it never spread, and was finally lost, with- 
out having been transmitted to the men of the age of the 
reindeer. 
M. Salomon Reinach, in his masterly ‘‘ Description 
