Letters to a Friend 



to collect proofs of the common measured arith 

 metical kind. 



On the 2 ist of Aug. last I planted five stakes 

 in the glacier of Mt. McClure, which is situated 

 east of Yosemite Valley, near the summit of 

 the range. Four of these stakes were extended 

 across the middle of the glacier. The first 

 stake was planted about 25 yds. from the east 

 bank of the glacier. The second 94 yards, 

 the third 152, and the fourth 223 yards. The 

 positions of these stakes were determined by 

 sighting across from bank to bank past a 

 plumbline made of a stone and a black horse 

 hair. 



On observing my stakes on the 6th of Oct., 

 or in 46 days after being planted, I found that 

 stake No. i had been carried down stream n 

 inches; No. 2, 18 inches; No. 3, 34; No. 4, 47 

 inches. As stake No. 4 was near the middle of 

 the glacier, perhaps it was not far from the 

 point of maximum velocity, 47 inches in 46 

 days, or i inch per day. Stake No. 5 was 

 planted about midway between the head of 

 [ 141 ] 



