ADDRESS BY PROFESSOR TRAILL. XXKV 
The author’s speculations on the source of the heat of thermal 
springs, partake of his views on the origin of volcanoes; namely, that 
it depends on the penetration of water, through fissures in the external 
erust of the globe, to the regions where he conceives the elements of 
earthy and alkaline bodies to exist: that the intense heat, generated 
during the oxidation of these elements, converts a portion of the water 
into steam ; which, under compression, obtains a high temperature, acts 
on various earthy bodies, and communicates its heat to subterranean 
waters which issue in thermal springs. This view he supports by nu- 
merous instances observed by geologists; especially by Professor Forbes 
in the Pyrenees, where thermal waters gush out in the vicinity of dis- 
ruptions, or upheavings of strata by ignigenous rocks. The author be- 
lieves that, unless in countries agitated by volcanic action, the tempe- 
rature of thermal springs is subject to little variation ; and that, where 
the contrary has been alleged, it may generally be ascribed to the im- 
perfection of the thermometers employed. 
The temperature of copious springs has generally been observed to 
vary little, and is about the mean temperature of the country where 
they occur. Thus the magnificent fountain at Vaucluse has the mean 
temperature of that part of France, and scarcely ever varies one degree 
of Reaumur. It is, however, worthy of remark, that I found the tem- 
perature of St. Winifred’s Well, the largest spring in Britain, by dif- 
ferent observations during twenty years, to experience variations of 
more than four degrees of Faht., always to have a temperature several 
degrees above the mean of Flintshire, and at all seasons superior to that 
of another very large spring, Fynnon asa, about five miles distant. 
The variations may perhaps arise from surface water, directly finding 
its way into the Holywell spring; but its constant superior tempera- 
ture may be accounted for, on Dr. Daubeny’s principle, from the dis- 
turbances in the strata produced by the numerous mineral veins in the 
adjacent Halkin Mountains. 
The second report is ‘On the Direction and Intensity of Teascheitid 
Magnetism in Scotland,’ by Major Sabine. 
The experiments were made at numerous stations, both by the sta- 
tical method of Professor Lloyd, in which the dip and intensity are as- 
certained by the same instrument, and by Hansteen’s method, of mea- 
suring intensity by the number of horizontal vibrations in a given time. 
It is interesting to know, that the intensities estimated by both methods 
nearly correspond ; and that we therefore may place confidence in either 
mode of observing, when allowance is made for changes in the force of 
magnetism in the needles employed. Major Sabine experienced, on 
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