In his December 1872 Overland Monthly article, "Living Glaciers of California" he wrote, "On the twenty-first of August last, I planted five stakes in the glacier of Mt. McClure. Four of these stakes were extended across the glacier, in a straight line, from the ease side to a point near the middle of the glacier. The positions of these stakes were determined by sighting across from bank to bank, past a plumb-line, made of a stone and a black horse-hair. On observing my stakes on the sixth of October, or in forty-six days after being planted, I found that stake No.1 had been carried downstream eleven inches; No.2, eighteen inches; No.3, thirty-four, and No.4, forty-seven inches. As stake No.4 was near the middle of the glacier, perhaps it was not far from the point of maximum velocity -- forty-seven inches in forty-six days, or one inch per day. Thus these ice-masses are seen to possess the true glacial motion." (John Muir Papers, December 1872 Overland Monthly "Living Glaciers of California")