the thermometer in summer stands around 112 degrees F. a great deal of the time, and reaches 118 degrees F. Yet Dr. Coues said he felt it no more than he did the summer heat of New York or Washington.* In winter the temperature at the bottom of the Grand Canyon is very mild, and flowers bloom most of the time.  One November I descended from the snow-covered top of the Kaibab to the Grand Canyon at the mouth of the Kanab, where I was able to bathe in the open air with entire comfort.

* I was at the Needles one summer for a brief time, and the air seemed very oppressive to me.

There are six chief topographical features, canyons, cliffs, valleys, mesa plateaus, high plateaus, mountains.  There are two grand divisions:  the lowland or desert, below the Virgen, and the plateau, but the topography of the immediate river course separates itself into four parts, the Green River Valley, the canyon, the valley-canyon, and the alluvial.  The canyon part is the longest, occupying about two-thirds of the whole, or about 1200 miles.  It is cut mainly through the plateaus.  The last of these southward is the Colorado, a vast upheaval reaching from the lower end of the Grand Canyon south-east to about where the 34th parallel crosses the western line of New Mexico.  Lieutenant Wheeler several times claims the honour of naming it (1868-71), but the name occurs on Lieutenant Ives’s map of 1858.  This plateau breaks sharply along its south-west line to the lowland district, and on its north-westerly edge slopes to the Little Colorado.  It bears a noble pine forest, and from its summit rise to over 12,000 feet the volcanic peaks of the San Francisco Mountains.  Its northern edge is the Grand Canyon, which separates it from its kindred on the other side.  These and the Colorado Plateau rise to from 6000 to 8000 feet above sea-level, and it is through this huge mass that the river has ground out the Grand Canyon, by corrading its bed down tremendously, the bottom at the end being only 840 feet above the sea, whereas the start at the mouth of the Little Colorado is 2690.  Yet here it is already 3500 feet below the surface at the end of Marble Canyon, which, separated only by the deep canyon of the Little Colorado, is practically a northward continuation of the Grand Canyon itself.  As the river runs, the Grand Canyon is 217 1/2 miles long.  To this may be added the 65 1/2 miles of Marble, giving a continuous chasm of 283 miles, the longest, deepest, and most difficult of passage in every direction of any canyon in the world.  The depth begins with a couple of hundred feet at Lee’s Ferry (mouth of the Paria), the head of Marble Canyon, and steadily deepens to some 3500 feet near the Little Colorado, where the sudden uplift of the Kaibab lends about 2000 feet more to the already magnificent gorge.  Along the end of the Kaibab the walls, for a long distance, reach their greatest height, about 6000 feet, but the other side is considerably lower than the north all the way