102 
THE MUSEUMS JOURNAL. 
[VOL. IO. 
In July, 1902, I saw, at quarters too close to be pleasant, 
along with Dr. Flett, the descent of one of the Incandescent 
Avalanches similar to the one that destroyed St. Pierre in 
Martinique, and brought forward the theory of the hot blast, 
which at first met with much opposition, but is now generally 
accepted. Briefly it is believed that the hot lava or magma, 
rising in the chimney of the volcano, is highly charged with 
gases and vapours which are retained in solution by the 
pressure. When it gets vent and the pressure is relieved, 
the whole is blown to pieces by expansion of the gases, and 
the result is a mixture of incandescent fragments, minute or 
larger, suspended in a mixture of gases and vapours also 
incandescent, which rolls down the mountain side by the 
force of gravity with the weight of a liquid and the mobility 
of a gas. 
In 1907 I revisited Martinique and walked a considerable 
distance up the valley, down which the avalanche descended. 
I saw the rocks grooved and scratched by the avalanches 
and hot blast which had repeatedly passed over them. The 
grooving thus produced, which much resembles glacial 
scratchings, is figured in Part II. of the Report to the Royal 
Society, published in the Philosophical Transactions for 1908, 
and the photographs are here reproduced in Plate VIII. It is 
entirely a surface action and the rock beneath is not decayed 
or crumbling, and it is in all respects different to the crumbling 
of our antiquities. 
Now the disease from which our stones are suffering is 
not a generalized surface abrasion like the above It is as 
strictly localized and circumscribed as a ringworm, which is 
a well-known parasitic disease, the part outside the border 
being absolutely free and unabraded, while the part inside 
is depressed, and the whole floor of the cavity is formed of a 
crumbling mass of grit. It would be impossible to find any¬ 
thing more different from the examples of wind action 
described above. It is not a surface action at all, but, I 
believe, a decay or rot affecting the substance of the stone, 
and, like other decays and rots, is in every probability caused 
by the action of some low organism, like the moulds and 
fungi which rot wood, canvas and other vegetable materials. 
About two years ago, to test this view and endeavour to 
find a cure, as all efforts based on the abrasion or chemical 
