TRANSACTIONS OF THE SECTIONS. 33 
neighbourhood, from 8. round by E. to N., while on the W. side outbuildings were 
unroofed or destroyed, the large garden wall thrown down, and the fencing around 
the plantations broken off and carried into the fallen timber. A few yards beyond 
the Fonds the gale reunited, and passing through a wood destroyed all the trees; it 
then proceeded across fields as far as Winthorpe, and here its fury became exhausted. 
The gale rotated in the direction of W. to 8., which was apparent from the twist 
of the wood of the snapped-off trees, and also from an avenue of chestnuts situated 
on the extreme eastern edge of the hurricane having all the torn-off boughs lying 
on the S. or storm-side, and being carried back beyond the level of the trees. 
Proposed Measurement of the Temperatures of Active Volcanic Foci to the 
greatest attainable Depth, and of the Temperature, state of Saturation, and 
Velocity of Issue of the Steam and Vapours evolved. By Rozurt Mater, 
C.E., M.A., FBS. 
The author having circulated the following document amongst various Members 
of the British Association a short time prior to the Meeting and during same, en- 
larged upon the objects of his proposed experimental inquiry ; and explained to 
Section A, in part, the methods he intended to employ. 
Determination of Voleanie Temperatures.—It is a singular fact, and one scareely 
creditable to the past investigation of volcanic phenomena, that up to this time no 
careful attempt has been made to determine, even approximately, the temperature 
of the heated or incandescent focus of any active volcano, even at the mouth of the 
crater, still less to depths lower down. 
Much labour and time have been lavished upon analysation of the gases and solid 
products evolved, and upon other still more minute inquiries—more than was ne- 
cessary, indeed, to obtain all the leading information as to the nature of yulcanicity 
(using that general term to express the train of forces and of events whence the 
supply of voleanic heat and energy is kept up) which such results are capable of 
yielding ; but the most obvious of all physical data, viz. those referring to the 
actual temperature of volcanic foci at the greatest attainable depths, have been 
completely neglected by vulcanologists, either because they too hastily concluded 
that experimental measurements of such were impossible, or, more probably, be- 
cause, as often happens in the investigation of nature, the most obvious question is 
that which is longest neglected being put to nature. 
The experiments that have been made on the heat of lava-fisswes, and upon the 
temperatures of geysers, hot-springs, mines, &c., do not of course bear upon those 
here in point. 
_ It seems almost unnecessary to dilate upon the importance to vulcanology, and 
to all cosmical physics, of some precise information as to these focal temperatures, 
the knowledge of which would assign limits at once to many speculations at pre- 
sent vague and perhaps valueless, give measure to the estimation of the forces con= 
ai and direct further investigation as to the sources whence these may be 
erived. 
For brevity, the writer may venturé to quote on this subject the following passiee 
from his Report to the Royal Society on the great Neapolitan earthquake of 1857 :— 
“T cannot find that any professed investigator of volcanos has ever thought of 
making the very obvious on important experiment of lowering, with an iron wire, 
a pyrometer as far as possible into a crater, in order to get some idea of its actual 
temperature, even within a few score yards of its mouth. 
“ When on Vesuvius, on the occasion of this Report, I feel satisfied that I could 
have so measured the temperature of the minor mouth—then in powerful action— 
to the depth of several hundred feet, had I possessed the instrumental means at” 
hand. To this smaller mouth it was then possible, b Minne the face in a wet 
cloth, to approach so near upon the hard and ahienly -defined (though thin and 
dangerous) crust of lava through which it had broken, as to see its walls for quite 
150 feet down, by estimation. They were glowing hot to the very lips, although 
constantly evolving a torrent of rushing steam with varying velocity. Accustomed 
as I have been by profession for years to judge of temperature in large furnaces by 
the eye, I estimated the temperature of this mouth, by the appearance of its heated 
Ss] 
1862, | 
