618 Extracts from the Minute Book of the Geological Society . 
where the perfect tube of half an inch diameter, meeting with a bed 
of pebbles of the size of kidney-beans, has dispersed and spread its 
agglutinating power, so as to form a mass of two and a half-inches 
in diameter, and in which the vitreous matter visibly surrounds each 
particle. In the course, however, of two or three inches more, it 
again assumes, on the opposite side of the mass, its usual tubular 
shape, and continues till it again meets with other obstacles. 
<c In its course about three feet from the surface, it had made an 
attempt to pass between two large pebbles about three-quarters of 
an inch asunder, by which effort it was much flattened, and its 
diameter much reduced ; each pebble was partially vitrified, but no 
adhesion had taken place. 
<c After that, for four or five inches, though going through soft 
sand, it became much contorted, as fig. 1. pi. 39. The lower the 
tube went, the more it seemed inclined to produce ramifications, 
some of such minute smallness, as not to be handled without 
breaking, but yet more perfect tubes than the large ones. One 
specimen I have is formed, as in fig. 2. pi. 39, from a ramification 
only-: the diameter of this complete little tube is not more than 
one-eighth of an inch, and its length about two inches. 
“ In its descent downwards, and at the depth of about six feet, it 
branched off in various directions, as in fig. 3. pi. 39. We fol- 
lowed the branch with minute accuracy, and the base terminated on 
a granite pebble, though not adhering to it, with a small ramifica- 
tion extending only a few inches. The diameter of the base of the 
tube, when it struck the pebble, was about one-quarter of an inch.” 
Note by the Editor. 
As the former notice respecting these tubes had not been accompanied by an engraving, 
the present opportunity has been embraced of giving figures of some of the specimens in 
the Museum of the Geological Society. Fig. 4. Plate 39 represents about one-half in 
length of the largest specimen drawn of the natural size. Fig. 5 is one that is forked 
and fig. 6, 7, 8 & 9 exhibit sections of various tubes. 
