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: Mineralogy and Geology. © 275 
“The effect of pressure on the conducting power of substances was also 
tried, and proved to be almost nothi A 
Saturation with moisture, on the other hand, produces 
In illustration of the use that may be made of the tables, we would refer 
to certain remarks made by Dr. Robinson on a paper read by Professor 
hill on 
e omer quite perceptibly, tilted or canted at one season to the east, at another, 
to the west. This he-at first attributed to the varying power of the sun’s 
 Tadiation to heat and’ expand the rock throughout the year; but he sub- 
: : wilde to 
: mi i ZY ? bf 7 
Varied.” With the light furnished by 
in an incfease of conductive power, but-the one whieh has ‘absorbed 
< Most water will have the greatest increase; and being thus the better 
ti i heat ow 
- eonductor, will draw a. portion fr 
‘to the surface—will' become in fact temporarily hotter, and, as a conse- 
quence, expand more than the other. In a word, rocks 
at the wet 
or 
? . : és 
Ses lt the hill to one side; at the dry season it 
*tpand most, and seem. to tilt d 
1th. The effect of discontinuity of substance iis — 
rmagh Observatory is erected, to be slightly, but toanastron- 
and the hill will seem to be tilted in the opposite di- 
AS Ne oe hag sat “s 
