44 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, No. 3 
Brussels were the International Geodetic and Geophysical Union and the 
International Astronomical Union. The former was divided into the Sec- 
tions of Geodesy, Seismology, Meteorology, Terrestrial Magnetism and 
Electricity, Physical Oceanography, and Voleanology. The International 
Astronomical Union was divided into a number of Committees, each of which 
deals with some phase of astromical science. 
It was proposed at Brussels that the two Unions should meet three years 
afterward at a time and place to be agreed upon. In the fall of 1921 the 
officers of the two Unions announced to the countries adhering to these 
Unions that the Italian scientists had invited them to meet in’ Rome, April 
20, 1922. This date was later changed to May 2 because a large conference 
had already been planned for the latter part of April in Rome and it would 
have been difficult for the delegates to the two Unions to secure satisfactory 
hotel accomodations. 
On the first day of the conference the delegates registered and presented 
their credentials, then attended the opening exercises at which the King of 
Italy and many other dignitaries were present. On the second day there 
were meetings of the two Unions. On the last day of the conference, which 
was May 10, there were also meetings of the two Unions, at which reports 
of certain committees which had been appointed during the first meetings 
were received, discussed and acted upon. During the intermediate days 
there were almost continuous meetings of the several Sections of the Inter- 
national Geodetic and Geophysical Union and of the Committees of the 
International Astronomical Union. 
Much work was done at Rome, although there was some feeling that the 
time was quite short for such a large gathering and so many interests. It was 
practically impossible for a delegate representing one branch of science to 
attend more than the meetings of his own Section or Committee. However, 
the delegates left Rome with a feeling that much had been gained and that 
International cooperation in science had been restored and is now on a very 
firm basis. 
Local scientists and officials entertained the delegates in the manner usual 
at such international scientific assemblages. 
Mr. Rosert S. Woopwarp, presented a paper on The compressibility of 
the Earth. It was discussed by Messrs. LAMBERT, HAwksworTH, Bowie, 
Curtis, and L. H. Apams. 
Author’s Abstract: This paper considers the earth as a gravitating mass 
of homogeneous, concentric spherical shells in which there is continuity of 
increase in density from the external surface to the center of the sphere. 
The mathematical problem thus presented is defined by four relations, . 
namely: (1) Poisson’s equation, connecting gravitational potential and 
density at any point of the mass; (2) the hydrostatic law connecting potential, 
stress and density at any point of the mass; (3) the hypothesis of Legendre- 
Laplace, postulating that the rate at which stress increases with density is 
proportional to the density; and (4) the law of conservation of mass. 
The problem is worked out on the assumption that the mean density of 
the earth is exactly twice the density of the surface crust. Data dependent 
on direct observations of the gravitation constant and on its relation to the 
mean density of the earth were cited to show that the mean density of the 
earth is very near to 5.514; while reference was made to the more recent 
investigations which seem to prove that the crustal density of the earth is very 
near to 2.76. 
Expressed in a conerete application, the resulting compressibility is such 
that if the pressure of the atmosphere were doubled the surface of ‘the earth 
