274 
waste chips. Nos. 1-8 and 11 are such supposable 
instances. Both parts of No.8 were pickedup. Few 
entire or finished implements occur, as they would 
not be left in these places unless lost. Nos. 9 and 10 
are complete; Nos. 12-14, roughly chipped and sup- 
posably unfinished. 
Proximity to the supply of chert has doubtless deter- 
mined this common occurrence of chippings in the 
sandy stretches near the lake. There is no evidence 
at hand of greater antiquity than the Indian. 
W. A. PHILLIPS. 
Evanston, Ill., Feb. 15. 
Tllusive memory. 
For some time past, I have been investigating a 
curious psychical or psycho-pathological experience 
which is alluded to by many writers upon psychology, 
and is not infrequently met with in general litera- 
ture. It is that vague sentiment of familiarity we 
sometimes have upon entering a new experience, 
best expressed in the words, ‘I have seen or known 
all this before.’ It has been explained by various 
writers, upon two widely different theories. The first 
is, that this ‘double perception,’ ‘double thinking,’ 
‘double presentation,’ as it has been variously named, 
arises from the dual structure of the brain, resulting 
in cases of imperfectly correlated action in two images 
or impressions not absolutely simultaneous: the lat- 
ter, therefore, is a repetition of the former, and gives 
rise to a sentiment that it has passed through the 
mind at some indefinite previous time. This theory, 
it will be observed, is a physiological one. The other 
theory is, that the phenomenon is a purely psychical 
one; that the false or illusory memory (Erinnerungs- 
tiuschung, Sander) has a real basis in some actual 
past presentation which is identical, or closely simi- 
lar, with the present one; or in some past images of 
the waking imagination, or dream- life, that, although 
these cannot be “recalled into consciousness, they are 
sufficient to give us the conviction that the present 
event is the repetition of a former one — why, or how, 
we do not know. There are several cases upon record, 
where this sentiment has assumed a pathological char- 
acter, and become a continual delusion, attending 
every experience. 
Two years ago, in the hope of obtaining more in- 
formation, I distributed a question upon the subject 
among a large number of persons, principally college- 
students. It may now be given in somewhat ampli- 
fied form, as follows: — 
Have you come suddenly upon an entirely new scene, 
and, while certain of ils novelty, felt inwardly that you 
had seen it before — with a conviction that you were 
revisiting a dimly familiar locality ? Mention, if you 
can, an instance or two in which this has occurred. 
Has any satisfactory explanation of this experience 
ever suygested ilself to you? How frequent is the 
experience in your case? Was it more frequent in 
childhood than at present? How soon do you usually 
become conscious of the deception? Does it occur more 
Frequently in connection with some kinds of experience 
than with others ? 
A quantity of material upon this subject has already 
been collected in this and other ways, which I hope 
to publish in a review article in April. In the mean 
while, any information bearing upon this question 
will be of great assistance and value to me. 
HENRY F. OSBORN. 
Princeton, N.Y., Feb. 23. 
Ripple-marks in limestone. 
The alternating limestones, shales, and sandstones 
of the upper coal-measures of Kansas are well ex- 
SCIENCE. 
[Vou. IIL, No. 57. 
+2 
posed along the ridges and water-courses near Eureka. 
Some of the limestone is thin-bedded, apparently due 
to interlaminated sheets of argillaceous material. 
The layers of limestone, however, seem to contain 
little foreign matter, certainly not more than the 
Trenton limestones (Buff) of Wisconsin and Minne- 
sota. The organic remains consist largely of crinoid 
columns, shells of brachiopods and lamellibranchs, 
and a few gastropod shells and cup corals. Nearly 
every layer of limestone shows these remains in great 
abundance firmly bound together by the highly crys- 
talline matrix. 
I have been thus particular in describing the lime- 
stone, that the conditions which made the following 
feature possible may be understood. Some six or 
eight slabs of this limestone in one of our sidewalks 
are clearly and distinctly ripple-marked. ‘This is the 
first instance of the kind that has fallen under my 
observation during ten years of state and private 
work in nearly as many states of the Union. 
The occurrence of ripple-marks in calcareous mud 
containing the remains of deep-sea, clear-water ani- 
mals, and interlaminated with argillaceous mud, is a 
combination not quite in accordance with the teach- 
ings of our text-books in geology. 
. C. WOostTER. 
Eureka, Kan., Feb. 23. 
A novel magnetic engine. 
It is a well-known fact that iron, when heated to a — 
red heat, ceases to be magnetic; so ‘that an armature, 
after being heated to redness, may be removed from 
its magnet by the expenditure of only a small fraction 
of the energy which is developed by the attraction of 
the same armature when it has cooled. 
Manifestly this fact might be employed in the con- 
struction of a motor, which, while of no practical 
value, is of theoretical interest, in which a perma- | 
nent magnet should act as the direct motive force. 
This has been done in the following manner. In 
the figure, abc represents a ring thirteen centimetres 
in diameter, “and supported hori- 
zontally upon radial arms and an 
axis of some non-magnetic metal. 
This ring is made of one or more 
turns of iron wire of about a mil- 
limetre diameter. NS is either 
a permanent or an electro mag- 
net. The axis is furnished with 
a driving-pulley, cord, and weight, 
as shown in the figure. 
That part of the ring which lies between a and ¢ is 
heated to bright redness by means of two or three 
Bunsen burners, The magnet then exerts a prepon-— 
derating attraction upon the farther or cool side au 
the ring, and the latter revolves as indicated by the 
