174 
One on Hawaii, near Punaluu, was found to have a nucleus of 
scoria eighteen inches in diameter, and around this successively a 
stony shell of three inches, a scoriaceous layer of fromone to two 
inches, a stony shell of from four to five inches, and then outside 
а rough lava shell six inches thick. One of large size, broken 
open on one side, had had its inside filling of scoria worked out by 
the natives, and so made into a small cave. A common size on 
Hawaii is from three to five feet in diameter ; but one enormous 
lava-ball, in the aa field west of Punaluu, measured 24 by 12 by 
9 feet in its extreme dimensions, and contained at least a thou- 
sand cubic feet. Enough of its hard outer shell was peeled off 
to ascertain that the second layer was quite vesicular ог scoria- 
ceous, and the next layer inside hard basalt again. These 
Hawaiian lava-balls lie in the midst of the other blocks of the 
aa stream, proving that all had a common origin, and that they 
are not projected bombs, and hence properly not bombs at all. 
Professor Dana! also refers in the following terms to the 
paper on **Fragmentary ejectamenta of volcanoes” by Dr. H. J. 
Johnston-Lavis?, who has studied with much care the Vesuvian 
lavas and eruptions. He (Johnston-Lavis) shows that the 
‘¢yoleanic bombs" of writers on European volcanoes are not 
bombs any more than those of Mt. Loa; that they were 
not projected into the air; that they occur sc: ittered. over 
lava streams in great numbers when the adjoining country 
is free from them, and occur within lava streams; that 
they vary in size from a walnut to some cubic yards, and yet 
have often a thin shell and friable nucleus; that they occur most 
commonly by far on lava streams whose surface is rough and 
scoriaceous instead of corded. He regards them as formed of 
lapilli that fell upon the flowing lava, and, in consequence of its 
forward motion, became incorporated with it, and may undergo 
partial fusion, but usually congeal around themselves a coating 
of the lava in which they are involved. Dr. Johnston-Lavis 
! Amer, journ. sci., 1888, ser, 3, vol. 36, p. 103. 
2 Proc. geologists’ assoc., London, vol. 9, no. 6. 
