Dryer is credited with being part of the first documented ascent of Mount St. Helens on August 27, 1853, together with three companions. He has also been reported as among the first party to climb Mount Hood, on August 8, 1854. This latter report has been disputed, with most historians claiming the Dryer attempt fell several hundred feet of the summit of Mount Hood, while an 1857 climb by Henry Lewis Pittock and four others provided better documentation of the summit having been reached.