-
5 degrees, slope of a very marked inclination. In France the high
roads must not exceed 4 degrees 46 minutes by law;
15 degrees, slope extremely steep, and which we cannot descend in a
carriage;
37 degrees, slope almost inaccessible on foot, if the ground be
naked rock, or turf too thick to form steps. The body falls
backwards when the tibia makes a smaller angle than 53 degrees with
the sole of the foot;
42 degrees, the steepest slope that can be climbed on foot in a
ground that is sandy, or covered with volcanic ashes.
When the slope is 44 degrees, it is almost impossible to scale it,
though the ground permits the forming of steps by thrusting in the
foot. The cones of volcanoes have a medium slope from 33 to 40
degrees. The steepest parts of these cones, either of Vesuvius, the
Peak of Teneriffe, the volcano of Pichincha, or Jorullo, are from
40 to 42 degrees. A slope of 55 degrees is quite inaccessible. If
seen from above it would be estimated at 75 degrees.)
Isolated volcanoes, in the most distant regions, are very analogous
in their structure. At great elevations all have considerable
plains, in the middle of which arises a cone perfectly circular.
Thus at Cotopaxi the plains of Suniguaicu extend beyond the farm of
Pansache.
