During the summer of 1854, in the Baltic, the British steamers employed
in examining the enemy’s coasts and fortifications took photographic
views for reference and minute examination. With the steamer moving
at the rate of fifteen knots an hour, the most perfect definitions of
coasts and batteries were obtained. Outlines of the coasts, correct in
height and distance, have been faithfully transcribed; and all details
of the fortresses passed under this photographic review are accurately
recorded.
It is curious to reflect that the aids to photographic development
all date within the last half-century, and are but little older
than photography itself. It was not until 1811 that the chemical
substance called iodine, on which the foundations of all popular
photography rest, was discovered at all; bromine, the only other
substance equally sensitive, not till 1826. The invention of the
electro process was about simultaneous with that of photography
itself. Gutta-percha only just preceded the substance of which
collodion is made; the ether and chloroform, which are used in
some methods, that of collodion. We say nothing of the optical
improvements previously contrived or adapted for the purpose of the
photograph: the achromatic lenses, which correct the discrepancy
between the visual and chemical foci; the double lenses, which
increase the force of the action; the binocular lenses, which
do the work of the stereoscope; nor of the innumerable other
mechanical aids which have sprung up for its use.