The few actinometer observations will be found in another part of the Appendix.
"Himalayan Journals V2."
J. D. Hooker
Exposure must be judged by an actinometer.
"Photogravure"
Henry R. Blaney
A very suitable instrument for timing the exposure of carbon tissue is Sawyer's actinometer.
"Photogravure"
Henry R. Blaney