604 
scientific departments in our State institu- 
tions, and I should be glad to call them 
generous. At least they have given Iowa 
the fame of men whose work in science has 
achieved national recognition. But these 
yearly appropriations, were they many 
times as great, could not supply the place 
of the great gifts, endowments to be for all 
time reservoirs of power transmuted con- 
stantly into the highest social service. It 
is the boast of American democracy that 
by such votive offerings it shows apprecia- 
tion of education, charity and scientific 
research. 
As members of a guild of workers in sci- 
ence, let us be thankful for even the hum- 
blest place. To discover any fact, how- 
ever trivial, to add anything, however 
slight, to the sum of human knowledge, 
this is to shape and dress some stone for the 
building of science, the home and shelter 
of the race. Our contribution may go to 
chink some crevice, or at least some master 
builder may find in it the keystone of an 
arch or the cap stone of a column. But 
whatever its place, if our work was well 
and truly done it abides as a permanent 
service to society. 
Witi1am Harmon Norton. 
CORNELL COLLEGE, MT. VERNON, IA. 
A NEW CONNECTION BETWEEN THE GRAV- 
ITY MEASURES OF EUROPE AND OF 
THE UNITED STATES. 
ABSOLUTE measures of gravity, repeated 
by different observers using different in- 
struments at identical stations, have shown 
comparatively large disagreements. The 
general experience has been that differen- 
tial measures of gravity are much more 
accurate than absolute measures, and there 
has, therefore, been a growing tendency to 
use the differential method rather than the 
absolute method. The results of such dif- 
ferential measures may be reduced to ab- 
solute units either by connecting by the 
SCIENCE. 
[N.S. Vou. XIII. No. 330. 
relative measures many stations at which 
absolute measures have been made and 
then making an adjustment to get a mean 
value, or a single determination of the ab- 
solute value of gravity, which is believed 
to be of a much higher degree of accuracy 
than any other, may be used in reduction 
to absolute units. 
These general conditions, especially with 
respect to gravity stations in Europe and 
the United States, led naturally to the 
campaign of differential gravity measures 
earried out by Assistant G. R. Putnam, of 
the Coast and Geodetic Survey, in the 
summer of 1900, under the direction of the 
International Geodetic Association. 
The compact and portable half-second 
differential pendulums known as A4, A5 
and A6, and of the type developed under 
the direction of Dr. T. C. Mendenhall while 
he was superintendent of the Coast and 
Geodetic Survey, were swung at Washing- 
ton in May and again in October, 1900. 
Between these dates they were also swung 
at the Kew University, Greenwich Obser- 
vatory, London Polytechnic Institute, Paris 
Observatory and at Potsdam, Germany, 
and thus served to determine with con- 
siderable accuracy the relative values of 
gravity at these points. Some of the prin- 
cipal previous determinations of gravity 
which have been made at or near these 
stations, and are therefore connected by 
the observations of 1900, are at Washing- 
ton, by Preston in 1889-90, and Defforges 
in 1893; at the Kew Observatory, by Heav- 
iside in 1873-74, by Herschel in 1881-82, by 
Walker in 1888, by Von Sterneck in 1893; at 
Greenwich Observatory, by Von Sterneck in 
18938 ; at the London Polytechnic Institute, 
by Sabine, Kater and Herschel; at the 
Paris Observatory, by Defforges in 1892, 
and Von Sterneck in 1893. At Potsdam 
the observations connect with a most elab- 
orate and painstaking determination of the 
absolute value of gravity which is now in 
