Personal and Scientific yei.cs. 
61 
For several years past I have with the assistance of our engineer, Mr. 
Preston C. F. West, been making rock temperature observations as we 
increased the depth at which the mining operations of the Calumet and 
Hecla Mining Co. were carried on. We have now attained at our deep¬ 
est point a vertical depth of 4,712 feet, and have taken temperatures of 
the rock at 105 feet, at the depth of the level of Lake Superior, 655 feet, 
at that of the level of the sea, 1,257 feet, at, that of the deepest part of 
Lake Superior, 1,633 feet, and at four additional stations each respect¬ 
ively 550, 550. 561 and 1,256 feet below the preceding one, the deepest 
point at which temperatures have been taken being 4,580 feet. We pro¬ 
pose, when we have reached our final depth, 4,900 feet, to take an addi 
tional rock temperature and to then publish in full the details of our 
observations. 
In the mean time it may be interesting to give the results as they 
stand. The highest rock temperature obtained at the depth of 4,580 
feet, was only 79° F., the rock temperature at the depth of 105 feet was 
59°F. Taking that as the depth unaffected by local temperature vari¬ 
ations, we have a column of 4,775 feet of rock with a difference of tem¬ 
perature of 20°F. or an average increase of 1°F. for 223.7 feet. This 
is very different from any recorded observations : Lord Kelvin, if I am 
not mistaken, giving as the increase for 1°F., fifty-one (51) feet, while 
the observations based on the temperature observations of the St. Goth- 
ard Tunnel gave for an increase of 1°F., sixty (60) feet. The calcula¬ 
tions based upon the latter observations gave an approximate thickness 
of the crust of the earth, in one case of about 20 miles, the other of 
26. Taking our observations, the crust would be over 80 miles, and the 
thickness of the crust at the critical temperature of water would be 
over 31 miles, instead of about 7 and 8.5 miles as by the other and older 
ratios. With the ratio observed here, the temperature at a depth of 19 
miles would only be about 470°, a very different temperature from that 
obtained by the older ratios of over 2,000°F. 
The holes in which we placed slow registering Negretti and Zambar 
thermometers were drilled, slightly inclined upward, to a depth of two 
feet from the face of the rock, and plugged with wood and clay. In 
these holes the thermometers were left for from one to three months. 
The average annual temperature of the air is 48°F., the temperature 
of the air at the bottom of the shaft was 72°F. 
New York Academy of Sciences. 
The section of geology and mineralogy of the New York 
Academy of Sciences held its regular monthly meeting Mon¬ 
day, December 16, 1895, Prof. J. J. Stevenson presiding. 
The first paper was by Prof. H. P. Cushing: “Notes on 
the areal geology of Glacier bay, Alaska.” The paper will 
appear in full in volume 15 of the Transactions of the 
Academy, but the following is an abstract: 
After an introduction which outlined the previous work in the region 
by Dr. H. F. Reid and the writer and the petrographical determination 
of the rocks that had been collected by them, and that had been studied 
by the late Dr. George H. Williams and the writer, a description of 
the general geology was given, based upon a geological map. 
Mr. Cushing shows that the rocks present are argillites, limestone, 
quartz diorite, (Jiorite, crystalline schists and dikes of diabase. The 
argillites have aVide distribution around the eastern side of the Muir 
Glacier basin, and also form the mountains adjacent to Muir inlet. 
They present three main phases : First, very hard, fine grained argillo- 
siliceous beds, gray to brown in color, occasionally approaching quartz¬ 
ite in character. Second, blue and black, somewhat slaty rocks, 
nearly as hard as the first, and equally fine grained, but less siliceous, 
although containing only a slight amount of calcareous matter. Third, 
