Yol. 66.] 
VOLCANO OF MATAVANU IN SAVAII. 
639 
Plate LI. 
An explosion as the lava falls into the sea.—This photograph, 
for permission to reproduce which I have to thank Capt. Allen, was taken by 
him from the cooled and solidified surface of the lava, near the spot where the 
still liquid mass from beneath was running into the sea, not far from the site 
of Toapaipai. Masses of red hot lava are seen in the air, each leaving a track 
of steam behind it. I saw many such explosions through t he binocular, but 
did not get near enough to obtain a photograph equal to this. 
Plate LIT. 
Lava in the lagoon, near Saleaula.—The lava in the background 
above high-water mark has cooled slowly, and had time to assume the usual 
corded structure. In the foreground, between tide-limits, many of the lobes 
have flowed into the water and been chilled before they had time to do this. 
They present a structure resembling one variety of pillow-lava. 
[Note.— The dates of the various lava-flows stated on p. 624 were taken in 
1909 from Amtmann Williams’s notes. The map on p. 622, with his latest 
corrections, was not received until the text w T as in type. The few small discre¬ 
pancies will not, it is hoped, materially affect the general narrative.] 
Discussion. 
Sir Archibald Geikie commented on the interesting character 
of the discourse to which they had listened, and on the instructive 
pictures which, as shown on the screen, had brought the details of 
a little-known volcanic region so vividly before their eyes. The type 
of volcanic action described by the Author belonged to that which 
had long been familiar as displayed by the Hawaiian volcanoes, 
hut a special value attached to his observations on the end of the 
lava-stream where it enters the sea. The speaker believed that 
never before had the phenomena there presented been so closely 
watched and so instructively photographed. The Author de¬ 
served infinite credit for the courage and persistence which, in 
spite of a trying temporary lameness, had overcome all the natural 
difficulties of the place, and had enabled him to bring home so large 
an amount of material for the elucidation of various problems in 
the mechanism of volcanoes. 
Mr. H. H. Thomas, referring to the motion of fluid lava beneath a 
solid crust, mentioned an area of 200 square miles of lava in Central 
Iceland, which was covered with subsidiary vents or spiracles rising 
to heights of 10 or 15 feet above the average surface. 
The President (Prof. Watts) said that he was much impressed 
by the Author’s description of the origin of pillow-lava. It had 
long been thought that this structure was the result of basic lava 
pouring into the sea, but this appeared to be the first case in 
which the actual production of it had been observed and described. 
The Author, in reply, said that the spiracles mentioned by 
Mr. Thomas were very abundant in the Myvatn district of Iceland, 
and were generally, and he believed correctly, attributed to the 
hot lava flowing over mud or similar wet material. The steam 
generated made its way up through the lava, escaped through 
cracks in the crust, and blew out masses of pasty lava which fell 
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