110 
RESEARCHES ON SOLAR PHYSICS. 
Explanation op the Plates. 
PLATE I. 
A. Represents the absolute length, in inches, of six lines, photographed in different parts 
of the field of the object-glass. The abscissee are the distances of the lines from 
the centre of the object-glass, the ordinates the corresponding lengths in inches. 
B. RR' represents the mean length of all observed lines in one direction, WW' the 
mean length of the lines measured in a direction perpendicular to the former. 
MM' is the mean length of all measured lines. The coordinates are the same 
as before. 
PLATE II. 
Represents the pinnacle of the Kew Pagoda as it appears on the photographs in different 
parts of the field. The measurement of the distances ab , a'b', cd, c'd' gave the 
length of the same lines in different parts of the field, while the distances aaJ, 
a'c , cd, W, Vd, dd! supplied the material for measurements in a direction perpen- 
dicular to the former. 
