/ 
Extracts from the Minute Book of the Geological Society . 617 
volcanic bodies, the earth is probably of meteoric nature. The 
specimen, however, from Hildesheim, destroys the grounds of this 
reasoning ; and it is most probable that the earth from Calabria, since 
it contains crystals of pyroxene, is volcanic. 
1818, Dec. 4. 
A letter from Edward L. Irton, Esq. was read, containing some 
further information respecting one of the vitreous tubes found at 
Drigg in Cumberland, an account of which was inserted in the 
2d volume. 
“ The remains of the third sand tube at Drigg have been disco- 
vered. Within the two first feet, we passed that bed of pebbles 
which (as has been formerly stated), diverted the direction of the 
tube. Following it downwards, within two feet more we came to 
a bed of smaller ones, closely bedded in wet sand ; through this 
the electric matter had apparently penetrated with difficulty, but 
with great force, as it adhered with strong vitreous firmness to 
every little pebble of the size of a kidney-bean or less that stood 
in its way. Its course through this wet sand was extended to the 
depth of nearly eight feet, when the tube became so very contor- 
ted and twisted in its course by the different pebbles it met with, 
as to assume a very different appearance. It passed two pebbles 
without adhering to either, though it was much flattened and com- 
pressed in its formation ; more so than what you observed in the 
specimens you procured when here. In one instance it had the 
usual tubular appearance, but at the distance of eight or nine inches 
was completely solid without any central perforation ; though on 
continuing its course lower down it again assumed the rugged and 
tubular shape. 
“ I have one or two specimens of a very singular conformation, 
4 i 2 
