According to B. Newhall (1), the technique known as combination printing evolved as a response to the problem of overexposure of the sky in landscape photography due to the sensitivity to the blue rays of the spectrum in the silver iodide emulsions used in the mid 19th century. The solution was the use of two different negatives with different exposure times of the same landscape to be combined in one print.
Gustave Le Gray (French, 1820–1884)
The Great Wave, Sète, 1857
Albumen silver print from glass negative; 33.7 x 41.4 cm (13 1/4 x 16 5/16 in.)
(1) B. Newhall - History of Photography, 1997 (5th revised edition) p. 73-74