PROCEEDINGS, 1859 — 1870. 
329 
would prevail a heat of which we have no conception. The sun would 
then return, and would remain 40 or ,'>0 days entirely above the 
liorizon, day and niglit, not low down, as is now the case in the Arctic 
re.iiions, but nearly vertical. Those only who have felt the fierce heat 
of a tropical sun, which remains scarcely more than 12 hours above 
tlie horizon, can imagine what would be the intense furnace-like heat, 
were the sun to remain nearly vertical during- 40 days and nights. 
The rocks on tlie surface, and even deep down in the earth, would 
become heated beyond anything which we liave ever seen, whilst the 
sulphurous strata would be forced into a volcanic condition. These 
and many other changes are probably occurring in Venus, for on that 
planet the sun does so remain above the horizon. 
In December, 1859, Dr. H. C. Sorby, F.R.S., read a paper on the 
temperature of the springs in the neighbourhood of Sheffield, in which 
he showed as the result of a number of experiments that the springs 
nearest the surface exhibited the greatest difference in temperature 
in summer and winter, and at the same time had the highest mean 
temperature. The springs which rise in the district, reaching an 
elevation of not more than 500 feet, had a mean temperature of 48^ 
degrees, whilst springs on higher elevations, reaching to 1,275 feet, 
had an average of about 45| degrees. Many springs in the neigh- 
bourhood of Sheffield are strong chalybeates. As a general rule there 
is small variation between the summer and winter temperature of 
these springs, which clearly points to their deep-seated origin, a con- 
clusion which is further established by their temperature being some 
degi'ees higher than that of the ordinary springs under similar circum- 
stances. Dr. Sorby concludes that this increased temperature pro- 
ceeds either from the greater depth from which the waters come, so 
that tl^ey experience the warming effects of the interior of the globe, 
or else that their temj^erature is somewhat raised by the oxidation of 
the pyrites of the subjacent strata, to which, no doubt, their chaly- 
beate character is due. 
Dr. C. W. Bingley, of AVhitley Hall, recorded the result of some 
experiments he had made on the properties of the different cWs for 
making firebricks. A considerable difference is well-known to exist 
in the tire-clays as regards their power to resist heat and mth- 
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