MELTOD OF PHOTOGRAPHIC SORVEVING. 513 
It may be interesting to state how I proceeded to arrive at 
the results hereafter given, and to point out the difficulties 
encountered. 
From views taken from the 865-foot base,—.about 1700 
feet from the glacier, which has a frontage of a mile—I1 plotted 
that part of the glacier that was intervisible; this gave me some 
thirty points on the glacier-front whose distance and height 
became known, and thereby the general contour and slope; the 
latter was found to be 1:3. This, of course, is far in excess of 
the slope of the glacial stream proper, which is found from 
our surveys to extend (the western branch) over fifteen miles in 
in a straight line into the interior and to have a slope of 1: 20. 
It may be mentioned that this branch and the Dawes Glacier 
emptying into Endicott Arm have the same névé. The mean 
slope of the Patterson Glacier, lying southeast of the Baird, is 
im (Heal MISS, 13 1 Be 
The difficulty in using a long base for photographing the 
face of the glacier is that it is then pretty difficult to recognize 
many points common to both stations. The photographs were 
taken on May 15, 19, July 13 and August 11, 1894. The near- 
est base station (No. 3) was about goo feet from the ice. The 
photographs taken from this station show most markedly the 
change and motion that took place between July 13 and August 
I 1,—twenty-nine days—on which dates views were taken too 
from station No. 1, 2065 feet from the former. Some fifteen 
points on the glacier were distinctly recognizable from both sta- 
tions, and hence plotted in distance and altitude. We had now 
a fairly accurate delineation of a part of the glacial front so that 
the distance to any point therein became well enough known to 
utilize for the purpose to be shortly explained. 
It is evident that from photographs from the same station 
but at different times changes are best seen. A photograph 
itself, however, only furnishes the angular measurement of any 
point thereon, both in azimuth and altitude, but not linear meas- 
ure. Hence, when we are comparing photographs of the same 
views from the same station, we must know the distances—or 
