Summit of Sierra Nevada - snow sheds in foreground, Donner Lake in the distance, Central Pacific R.R.

Miles of roofed timber built over a railroad because of snow that is not in the picture. Andrew J. Russell photographed the Central Pacific summit in summer, which is the only season you could see what had been built.

Shows: The scale of what a winter's snow was worth spending money on, in the decade before anyone was measuring it.

What this does not let you conclude: Snow. This is a summer view, and the sheds are the evidence -- the thing itself is out of frame for half the year, which is roughly the problem snow surveying was invented to solve.