1899.] NATURAL SCIENCES OF PHILADELPHIA. 123 



Photography seems to offer the most satisfactory means of per- 

 manently recording the position of the ice from year to year. On 

 our visit, therefore, to the Great Glacier in 1898, a large rock was 

 chosen on the south side of the trail, below the bridge, and some 

 iive hundred yards from the ice foot. The 1898 test view was 

 taken from this position on the 19th of August (PI. Y). The 

 smal) moraine in the lower right-hand corner is the one mentioned 

 by Dr. Green, and shown in the pictures of 1887. The large 

 rock marked " E " Avas then partly encased in the ice, as will be 

 seen in the centre of the 1887 picture, and forms a most excellent 

 point for identification (PI, IV). In conjunction Avith the photo- 

 graph a number of range rocks on the moraine were selected and 

 marked for identification. The rocks " B" and " D" on the 

 photograph were chosen because they were of unusual size, and 

 were far enough from the ice to prevent any movement. A line 

 drawn between them August 17, 1898, passed eighteen inches 

 below the extreme snout of the glacier at " H." " B " is a large 

 rock, with a triangular black mark on the north side. It was 

 lettered with Venetian red paint as follows: 



•e6(-iI-IIIA 

 VIII-17-'98. 



"D" is a yellow rock which has been split in halves. It was 

 marked on one piece, " Rock opposite lines with snout, VIII-17- 

 '98," and on the side opposite with a vertical line and two arrows. 

 The rock " G " was not marked, but may be easily identified by 

 the photograph. Its highest point was fifty -nine feet to the nearest 

 ice on August 17, 1898. 



To locate the position of the snout, the rock " C," a long, 

 rounded boulder, was chosen. It was marked " 60' 0" to snout, 

 VIII-17-'98," and with arrows. 



During the warm weather of August the rate of recession was 

 very rapid, and a few days made a marked change in the posi- 

 tion of the ice. October 24, 1898, Mr. Hugh B. Walkem, of 

 Vancouver, visited the glacier and compared the position of the 

 ice with the rocks marked by us, sixty-eight days before. He 

 found that the snout had receded forty-six feet in that interval, or 

 eight and one-tenth inches per day. 



As respects the annual rate of recession it is hard to obtain reli- 



