212 
ME. KOBEET MALLET OX YOLCAXIC EXEEGY. 
Etna, 1G69: GOO millions cubic metres, according to Borelli, but on very unsatis- 
factory data. 
M. Cordier (Essai sur la Temperature de 1 Interieure de la Terre, &c.), after dis- 
cussing several of the greatest lava-streams on record, including the above, and admitting 
their uncertainty, comes to the conclusion that 1000 millions of cubic metres exceeds 
the extreme volume of any lava-stream of which we have any evidence whatever. 
This applies to lava-streams from volcanic action proper, and excludes those enor- 
mous wellings forth ( epanchnents ) of basalt, trachytes, or other ancient lavas antece- 
dent to the existing epoch of true or explosive volcanic action, such as have been observed 
in California, the magnitude of which often wholly dwarfs that of the very greatest 
volcanic outpourings. 
The writer believes all the greater figures preceding, including M. Cordier’ s estimate, 
to be greatly in excess of the truth ; but let us adopt M. Cordier's volume. Let us 
further assume that, in addition to this 1000 million cubic metres of material all fused, 
we have the same proportion as present supposed of heated but not fused incoherent 
material, viz. twenty times the volume of lava ; and, lastly, that the entire is lifted from 
ten miles depth, and, in addition, to the summit of a cone higher than ITecla, or 5280 
feet (=1 mile) more, and that, as before, we have double as much lifting work wasted as 
is usefully employed, i. e. three units of heat to do the work of one. 
We then obtain the following results: — As there is l - 30 7 cubic yard in 1 cubic 
metre, 1000 millions of cubic metres =1307 millions of cubic yards fused from 300° 
Eahr., requiring 9- 9 cubic yards, or nearly 10 cubic yards, of crushed rock for each 
cubic yard fused, =10x1307 = 13070 millions of cubic yards of crushed rock. 
Then for heated material raised from 300° to 1000°, we have 20x1307=26140 mil- 
lions of cubic yards, requiring 3-8 cubic yards of crushed rock for each cubic yard 
heated, or 3*8 X 26140 = 993320 millions of cubic yards of crushed rock. 
Then for the lifting work, taking the density at T2 ton per cubic yard, or T2 ton 
X (993320 millions + 13070 millions) =1006390 millions of tons lifted; and as 3°=1 
foot-ton, 
1006390 millions 
3° 
= 335463 million units of heat to lift it 1 foot high ; and dividing 
by 6472 units of heat in 1 unit of volume of crushed rock, we require 50*3 cubic yards of 
crushed rock to lift 1 foot high, or 50‘3 X 5280 = 265584 million cubic yards to lift 1 mile 
high, or 11 times this for 11 miles, in all =2921424 million cubic yards of rock crushed. 
Then for wasted heat we have double this, or 5842848 millions of cubic yards of 
crushed rock. 
Summing up our results, we have : — 
Fusing work = 13070 million cubic yards. 
Heating work = 993320 „ 
Lifting work =2921424 „ 
Wasted work =5842848 „ 
Total in cubic yards of crushed rock . . 9770662 
