San Juan and Key West, furnish information of value in connection with the formation and movement of hurricanes.
Another example of mutually helpful co6peration in pilot balloon work is the furnishing of equipment, through the department of terrestrial magnetism of the Carnegie Institution, to the Apia Observatory, Samoan Islands. In this case also copies of the observations are forwarded to the Weather Bureau for study. R.
Kilauea Volcano
Observatory. (Clip Sheet U. S. Department of Agriculture No. 278, October 22, I923.)--A field of activity of the Weather Bureau of the United States Department of Agriculture that is but little known is the volcano investigations conducted on the island of Hawaii under Dr. T. A. Jaggar, Jr. The permanent scientific staff consists of a volcanologist, a seismologist, and a chemist. Occasionally chemists, geologists, seismologists, and physicists, both from the United States and from foreign countries, spend from a few weeks to several months at the Volcano Observatory.
The observatory is situated about 4ooo feet above sea level on the brink of Kilauea Volcano, which is continually active, with a lake of molten lava. Studies are made not only of that volcano but also of Mauna Loa, nearly IO,OOO feet higher, which erupts every five or six years. The eruptions of the two volcanoes are not explosive but take the form of a rather quiet extrusion of molten lava.
The routine of the station consists in daily observation and photography of the fire pit, frequent surveys to determine the height of the lava, care of several seismographs, and interpretation of seismograms. The seismograms give the distance and direction of earthquakes--five or six occur each week--and indicate the amount of tumescence or subsidence of the entire mountain top. From these seismographic data forecasts of volcanic activity from two or three hours to several days in advance are often made.