The others looked at him, surprised at the depth of his reaction.
As the same stream sometimes changes abruptly from one kind to the other, the two kinds must be due to different conditions affecting the flow, and among the conditions which may cause a stream to break up into the aa have been mentioned the greater depth of the stream, a sluggish current, impediments in its course just as it is granulating, and, what is more probable, subterranean moisture which causes it to cool from below upward instead of from above downward as in the pahoehoe.
The communication between the Atlantic and Arctic basins being cut off, as already described, at a depth of about 300 fathoms, the temperatures in the Norwegian Sea below that level are essentially Arctic, usually below the freezing-point of fresh water, except where the distribution is modified by the surface circulation.
This experiment may be varied by holding the fork over a glass jar into which water is poured to such a depth that the air-column within reinforces the note of the fork when suitably placed, and then turning the fork round.
Below the freezing point of water, the summer heat merely thawing the surface to a depth of about 3 ft.
Later apparatus, such as Pettersson's bifilar current-meter or his more recent electric-photographic apparatus, and Nansen and Ekman's propeller current-meter, measure both the direction and the velocity at any moderate depth from an anchored vessel.
At Lucknow a boring was driven through the Gangetic alluvium to a depth of 1 33 6 ft.
Before it receives the Voronezh the Don has a breadth of 500 to 700, or even in a few places loon ft., while its depth varies from 4 to 20 ft.; by the time it reaches its most eastern point the depth has increased to 8-50 ft., and the ordinary breadth to 700 -1000 ft., with an occasional maximum of 1400 ft.; in the lowest division the depth is frequently 70 ft., and the breadth in many places 1870 ft.
Buchanan pointed out in 1876, that the great contrasts in surface salinity between the tropical maxima and the equatorial minima give place at the moderate depth of 200 fathoms to a practically uniform salinity in all parts of the ocean.
And softened lights, combined with depth and delicacy of hjame.