Janssen Solar Photograph and Optical Studies. 301 
tosphere to a field of grain in which from a bird's-eye view, we 
see, in a calm, only the rounded summits of the wheat. ta 
wind blow fitfully over the surface, bending the crests here and 
there and showing more of the form of the straws. This is, it 
seems to me, the suggested explanation of the elongated form of 
the “grains” shown in such an interesting manner in M. Jans- 
nomena, and it would be doubtless desirable, if possible, that 
before us, demand not only the finest mechanical and chem- 
ical methods and still more the highest skill, but atmospheric 
conditions so brief as to rarely or never last during even the 
short time mentioned. 
Finally, then, though without two pen ia Of equal-ehr 
es er, it is perhaps 
Allegheny, Penn., March 14, 1878. 
