May 27, 1862: Mount Diablo
Camp 70I resolved to make another measurement of the mountain for the sake of seeing where some errors lay in our previous measurements, and also to determine the altitude of the northeast peak, which we have named Mount King. So that morning I started, with Averill and two barometers, leaving Hoffmann at camp to observe station barometer. A citizen went with us to find the trail, for the people of Clayton have resolved to spend a hundred dollars in making the trail passable for “travelers,” to attract visitors.
The morn was gloriously clear, but before arriving at the summit cold winds and clouds came on, which hung over the summit at intervals during the day. There are two peaks, one about three hundred feet below the other, and between them a gap. Leaving Averill on the main peak, I descended into the rocky gap over eight hundred feet below. Through this gap the wind roared with a violence almost terrific at times—the temperature only 44° to 46°—and at intervals the clouds rushed through like a torrent. I spent an hour and a half, observing every fifteen minutes, in that peculiarly grand spot—not grand because of the view, but because of the surrounding rocks and the clouds which rushed among them, dissolving again after leaving the mountain, driven by the fierce wind that was concentrated by coming up a canyon that had its head in this gap.Then I took my way along the crest to Mount King. It is but half a mile from the gap, but it is a crest of naked rocks, over and among which one has to pick his way, not always without danger. I spent two and a half hours in observations. The wind was not so high, and the clouds enveloped me only once, but they hung much of the time over the main peak where I had left Averill and our companion.
I shall never forget those hours. The solitude—total silence save the howl of the winds in the gap below—the cragged rocks around me, and the enchanting scene spread out below—the great San Joaquin plain seeming more like a sea than ever—cloud shadows chasing each other over the green hills at the base of the mountain—and the clear blue sky in the southeast beyond the reach of the clouds that formed over our summit. The distant Sierras were in view, but not with that distinctness with which we saw them before.
I got back to the other peak, joined my shivering companions, and we were back before sunset, tired enough. But we were to leave the next morning and a month would elapse before I could mail letters again, so after making calculations, I wrote until midnight.We have made five measurements, but have discarded two that were made under the poorest circumstances, saving only the best. Let me tell you how they agree: height of Mount Diablo above mean tide—(a) 3,879.6, (b) 3,876.0, (c) 3,874.1: mean 3,876.4 feet.10 These three measurements varied less than five and a half feet, from the lowest to the highest, although the distance from the summit to the tidewater (at Martinez) must be over fifteen miles. We have made a most accurate observer of Averill. These measurements are the result of eighty-two barometrical observations, and not less than three hundred have been taken on all our work in this vicinity.
Specimens collected, May 22-27: Eriodictyon californicum; Eschscholzia californica; Camissonia micrantha; Linanthus ciliatus; Linanthus androsaceus; Zannichellia palustris; Vulpia microstachys var. confusa; Lithophragma bolanderi; Fragaria vesca; Lithophragma affine; Luzula comosa; Lupinus bicolor; Carex globosa; Trifolium willdenovii; Aquilegia formosa; Calochortus albus.