DECEMBER 22, 1899. ] 
are selected seedlings, and 14 per cent. chance 
seedlings, or wildlings. In pears, plums and 
other fruits important developments due to 
hybridization were pointed out, and special at- 
tention was called to the plum where a gradual 
amalgamation of our native plum with the 
Japan plum, Prunus triflora; and apricot plum, 
P. Simoni, is being brought about which bids 
fair to ultimately revolutionize plum culture. 
Instances were also cited where epoch-making 
improvements had been secured in corn, wheat, 
peas and tomatoes. 
O. P. Hay discussed ‘The Chronological Dis- 
tribution of Elasmobranchs’ presenting a dia- 
gram which showed by means of one set of 
curves the chronological distribution of the 
species of North American elasmobranchs and 
by another set the distribution of those of 
Europe. A table was also given which showed 
the genera belonging to each of the geological 
periods. The relationship of the paleozoic 
families of skates to those of the Neozoic was 
also considered. 
O. F. Coox, 
Secretary. 
PHILOSOPHIOAL SOCIETY OF WASHINGTON. 
AT the 506th Meeting of the Society held at 
the Cosmos Club, November 11th, informal 
communications were made by Dr. A. Martin 
on the extraction of the 4th root by successive 
subtractions; and by Mr. Marcus Baker, on his 
recent duties in Paris in connection with the 
Venezuelan boundary arbitration. The first 
regular paper was by Mr. R. H. Strother, on 
“Some Observations on a Problem in Dynamics.’ 
The problem was how a cat turns over in the air, 
and was illustrated by Professor Marey’s’ photo- 
graphs of a cat turning over while falling, and 
by a model which performs the same feat. The 
model consists of two cylinders of wood con- 
nected by elastic bands. Each of the cylinders 
describes a continuous complex motion, one of 
the components of which is a rotation about its 
longitudinal axis, the motion being such that 
the sum of the moments of momentum is con- 
stantly equal to zero. It is possible for a ring 
to describe a motion in its own plane such that 
its moment of momentum is zero, but involving 
a rotation of the ring about its center. 
SCIENCE. 
933 
Following this paper, Mr. J. Elfreth Watkins 
gave a chapter from the early history of me- 
chanics. 
The 507th meeting was held November 25th 
in joint session with the Chemical Society of 
Washington and was devoted throughout to the 
Atomic Theory. Papers were read by Messrs. 
J. S. Ames, F. H. Bigelow, H. N. Stokes, Cleve- 
land Abbe and F. K. Cameron. A general dis- 
cussion followed, in which members of both 
societies participated. ‘ 
E. D. PRESTON, 
Secretary. 
ANTHROPOLOGICAL SOCIETY OF WASHINGTON. 
THE 295th Regular Meeting of the Society 
was held Tuesday, November 21, 1899. 
Mr. Wm. F. Willoughby read a paper on 
‘The Housing of the Laboring Classes in Eu- 
rope with Special Reference to France and 
Belgium.’ 
Mr. Gustavus A. Weber read a paper on 
the ‘Housing of the Laboring Classes in the 
United States,’ and Dr. Geo. M. Kober pre- 
sented a paper entitled ‘The Housing of the 
Laboring Classes in the City of Washington,’ 
in which he said in part that the question of 
housing the wage-earners in cities is one of ex- 
treme interest to students of sociology and 
municipal hygiene, and the movement to 
supply improved, wholesome houses at reason- 
able rentals in the National capital owes its 
beginning largely to the labors of members of 
the Civic Center and of the Woman’s Anthro- 
pological Society. 
The Civic Center Committee on housing the 
people has for its fields of work, the investiga- 
tion of the alley houses and slums with special 
reference to sanitary and sociological condi- 
tions, and their effect upon the health and 
morals of the inhabitants. 
From the results of this investigation the 
objections to our alleys may be summarized as 
follows : 
1. The existence of blind alleys or cul-de- 
sacs shutting off small communities from the 
outside world, and which are calculated not 
only to promote sickness, but also immorality 
and crime. 
2. Insanitary conditions of the alleys and 
