APRIL 26, 1901.] 
progress under the direction of the Inter- 
national Geodetic Association, and which 
is expected to yield the most reliable value 
ever yet determined in absolute units. 
Other connections of varying degrees of 
accuracy had previously existed between 
these six stations. The new measures fur- 
nish direct connections of a very high de- 
gree of accuracy. These six stations have 
directly or indirectly been connected by 
various observations with nearly all the 
gravity stations of the world. 
The work of deducing from the numerous 
connections between the gravity measures 
of various countries the best absolute 
values of gravity at the many points of ob- 
servation scattered over the whole globe is 
peculiarly the duty of the International 
Geodetic Association, and is being per- 
formed systematically by that organization. 
In this investigation the gravity observa- 
tions of 1900 furnish important new evi- 
dence. 
The special value of these gravity meas- 
ures of 1900 to the Coast and Geodetic 
Survey lies in the fact that they furnish the 
means of.reducing accurately to absolute 
units all the relative measures made in the 
United States with the half-second pendu- 
lums during recent years. These values 
have up to the present time been reduced 
approximately to absolute units by assum- 
ing that the value of gravity at the Coast 
and Geodetic Survey Office is 980.098 dynes. 
This approximate value was adopted in 
1892 and depends upon an absolute deter- 
mination of gravity at Hoboken, N. J., and 
three comparisons of Hoboken with Wash- 
ington by relative measures with three dif- 
ferent sets of pendulums, and finally an 
absolute determination at Washington in 
1889-90. In i894 Mr. Putnam derived 
twenty-nine different values for gravity at 
Washington by utilizing all the connections 
available at that time between Washing- 
ton and various stations at which absolute 
SCIENCE. 
655 
measures had been made by various ob- 
servers from 1792 to date. The mean of 
these values was 980.107. As the individ- 
ual determinations showed a wide range, 
0.147, the value 980.098 cited above was 
retained. From the relative observations 
of 1900, combined with the preliminary 
published absolute value of gravity at Pots- 
dam from the observations which are still 
in progress, the value of gravity at Wash- 
ington is 980.111. This differs by one part 
in 77,000 from the approximate value 
adopted in 1892, and by only one part in 
250,000 from the mean of the 29 values de- 
duced in 1894. 
JoHn F. Hayrorp. 
THE AMERICAN INSTITUTE OF ELECTRICAL 
ENGINEERS. 
TuHE first conversazione of the Institute 
was held at Columbia University on the 
evening of April 12th. About 1,500 ladies 
and gentlemen attended and enjoyed a most 
pleasing entertainment. Through the 
courtesy of the University authorities every 
facility in the way of space, current supply 
and assistance in preparing exhibits was 
placed at the disposal of the exhibitors, so 
that the many new devices, etc., were shown 
in actual operation. The list of exhibitors 
was long and the character of the apparatus 
extremely varied, as might be expected from 
a function held under the auspices of a 
society which represents the connecting 
link between pure science and commercial 
engineering. Many of the names included 
are well known in scientific circles, but the 
exhibits were in every case novel and have 
created a standard which will tax the 
energies of the Institute to the utmost to 
repeat in future conversaziones. Many 
notable persons were present as guests of the 
Institute, among them President Low and 
numerous professors of Columbia. Presi- 
dent Low was accompanied by Baron von 
Holleben the German Ambassador to this 
