42 
The Secretaries communicated a paper by Professor Gus- 
tavus Hinrichs, of Iowa City, United States, entitled, “ On 
the Boiling Point of the Isomers C 4 H 14 0.” Professor Roscoe 
stated that from the speculative character of the communi- 
cation and the nature of the symbols employed by the 
author, it was impossible to give an intelligible abstract. 
“On Measurements of the Chemical Intensity of Total 
Daylight made during the recent Total Eclipse of the Sun, 
by Captain J. Herschel, R.E.,” by Professor H. E. Roscoe, 
F.R.S. 
The following communication contains the results of 
observations upon the varying intensity of the chemical 
action of total daylight during the total eclipse of the sun 
on August 18th last, made at Jamkhandi (75° 20' E.; 16° 80' 
N.), in India, by Lieut. John Herschel, R.E. The method 
employed was that described by me in the Bakerian Lecture 
for 1865 {Phil. Trans., 1865, p. 605), and consists of the com- 
parison of tints effected by the total daylight acting for a 
given time upon uniformly sensitive chloride of silver paper. 
The weather at Jamkhandi during the eclipse was most 
unfavourable for such observations. Lieut. Herschel writes 
that “ in truth nothing could have been more disturbing 
than the constant and rapid hurrying over of cloud of all 
decrees of darkness at low altitudes combined with lioht 
fleecy ones, nearly stationary, at a greater height.” At no 
time during the eclipse did the estimated amount of cloud 
fall below 4, the average being about 7, and frequently the 
sun was obscured by heavy cloud, though at intervals it 
shone clear and bright. 
By arranging the 42 different observations of the inten- 
sity of total daylight into 9 groups, we eliminate the varia- 
tions among the separate consecutive observations arising 
from the unfortunately variable state of the weather, and 
obtain the following series of regularly diminishing and 
