WHITNEY, Mount, a peak of the Sierra Nevada, in the southeastern part of California; altitude, 14,522 feet. It is the highest elevation in the United States, outside of Alaska. On the east side the slope is precipitous, rising abruptly from Owens Valley about 11,000 feet. In 1881 Prof. S. P. Langley remained for some time on the summit, making daily observations on the solar heat.