We recently received a link on a Sierra Club leaders' forum to this website:
http://jim.4lipmans.com/RLL/index.html
It contains photos of 1914 and 1915 Sierra Club outings to Yosemite. Lots of wonderful old shots of the area, and of historic figures.
These were digitized by Jim Lipman, whose father Robert Lipman took them all. In the 1914 set, Lipman is shown in photo #170. #39 shows a great pair of hobnailed boots. #162 shows William Colby, secretary of the Club for 46 years, under a massive tree in Hetch Hetchy valley (this was the last Sierra Club trip that was able to camp in the valley).
I hope that you enjoy seeing these as much as I did!

