Marcu 15, 1901.] 
Faxon’s belief, the author contended that the 
fifth group of crayfish, including southern 
United States and Mexican species, is the most 
generalized and resembles Cambaroides most 
closely.. This would seem to indicate that the 
theories of Huxley and Faxon to explain the 
distribution of the Astacide will not hold good 
and that the original home of the Astacine pro- 
genitors was in southern seas and invaded the 
continents from that direction. It was further 
“stated that the specialization of Cambarus is 
probably much more ancient than the special- 
ization of Cambaroides, and that the resemblance 
between Cambaroides and Cumbarus is accidental 
and does not indicate a close relationship. 
M. B. Waite spoke of the ‘Influence of Vege- 
tation on the Sand Formations of the Michigan 
Lake Shores,’ his remarks being illustrated by 
lantern slides. He showed how dunes may 
originate by the sand being at first held im 
check by grass, which grows upward and out- 
ward as the sand accumulates, and illustrated 
the gradual progress inland of dunes and the 
manner in which the sand moved slowly for- 
ward in great waves to overwhelm the adja- 
cent country. 
F. A. Luoas. 
' PHILOSOPHICAL SOCIETY OF WASHINGTON. 
THE 530th meeting of the Society was held 
February 16, 1901. Mr. R. H. Strother called 
attention to the fact there are now three proc- 
esses of making phonographic records that 
promise to be permanent, so that the early idea 
of making records of speech for posterity now 
seems feasible. 
Mr. R. A. Harris read a paper entitled, ‘A 
Few Questions in Hydrodynamics.’ This re- 
viewed briefly the kinds of problems in liquid 
wave motion which have been considered in 
articles and treatises on hydrodynamics. But 
its chief object was to point out the lack of at- 
tention given to oscillations in bodies-of water 
haying incomplete boundaries, although a some- 
what analogous subject, viz., that of the open 
organ pipe, had received much attention. The 
behavior of water in straits is also a neglected 
subject. The case treated by Airy really ap- 
plies only to motions in straits not extremely 
short, and where the bodies connected are com- 
SCIENCE.” 
429 
paratively deep. These and other hydrody- 
namical questions, it was contended, must be 
investigated before satisfactory progress can be 
made in the theory of tides. 
Mr. J. F. Hayford presented the ‘ Recent 
Progress in Geodesy,’ referring to the triangu- 
lation in progress on the 98th meridian; the 
connection of the principal United States and 
European stations by pendulum observations ; 
the connection recently made between several 
independent systems of precise levels, so that 
the elevations of some 4,000 places have now 
been published ; and the results of the calcula- 
tions of the axes of the terrestrial spheroid based 
on the United States observations. [This paper 
appeared in Sorence for March 8th.] A 
spirited discussion followed regarding the ac- 
curacy of the new and rapid base-line measure- 
ments, and the leveling between the Gulf of 
Mexico and the Atlantic Ocean. 
CHARLES K. WEAD, 
Secretary. 
AMERICAN MATHEMATICAL SOCIETY. 
A REGULAR meeting of the American Mathe- 
matical Society was held at Columbia Univer- 
sity, New York City, on Saturday, February 
23, 1901. About thirty persons attended the 
two sessions. The President of the Society, 
Professor Eliakim Hastings Moore, occupied 
the chair. The following persons were elected 
to membership: Professor John F. Downey» 
University of Minnesota ; Professor F. C. Ferry, 
Williams College; Mr. H. T. Gerrans, M.A., 
Oxford University; Mr. Edwin Haviland, Jr., 
New York City; Professor A. E. H. Love, Ox- 
ford University; Mr. V. R. Thyagarajaiyar, 
Bangalore, India. Two applications for mem- 
bership were received. 
The following papers were presented at this 
meeting: 
(1) Dr. H. E. Hawkes: ‘ Note on Hamil- 
ton’s determination of irrational numbers.’ 
(2) Professor E. B. VAN VLECK: ‘On the 
convergence of continued fractions with com- 
plex elements.’ 
(3) Dr. M. B. PorTEeR: ‘On linear homoge- 
neous finite difference equations, with applica- 
tions to certain theorems of Sturm.’ 
