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14 PHILUSOPHICAL SOCIETY OF WASHINGTON. 
were greater still. The lava has a high liquidity and flows forty 
to fifty-five miles, spreading at the base of the cone into a broad 
sheet. There are no explosive phenomena and no fragmental pro- 
ducts. The slope of the mountain is 4° along the major and 7° 
along the minor axis. Kilauea has a few cinder cones on its flanks. 
-Mauna Kea consists chiefly of them, and has an average slope of 
#4° 011°. 
Kilauea is always active, maintaining lakes of liquid fire.’ Over 
one of these a crust is formed, black, but flexible, which after a 
while breaks up and suddenly sinks, the process being repeated at 
intervals of 14 to 2+ hours. The great interior pit described by 
observers from 1823 to 1841 is now filled. 
Mauna Loa is not active more than one-third or one-fourth of 
the time, but compensates by the magnificence of its phenomena. 
Great fountains of lava are projected hundreds of feet into the air. 
Mr. Dutton’s communication was interrupted by the arrival of 
the hour for adjournment. In response to a question by Mr. Tay- 
LOR, he stated that the crust over a lava lake acquired a thickness 
of five or six inches before breaking up. 
Mr. ANTISELL inquired whether there is any basalt on the 
islands, and Mr. Dutton explained that they are composed exclu- 
sively of that material. 
231st MEETING. Marcx 10, 1883, 
Vice-President WELLING in the Chair. 
Thirty-four members and visitors present. 
The Chair announced that Messrs. ALBERT WILLIAMS, Jr., 
JoHn Henry ReEnNsHAWE, and Henry Francis Wauuine had 
been elected to membership. 
Mr. M. H. Doo.irt_e read a communication on 
SUBSTANCE, MATTER, MOTION, AND FORCE, 
which was discussed by Messrs. W. B. Tayitor, Evtiorr, HarK- 
NEss, and WELLING. 
Mr. E. B. ELLIoTr then communicated 
