[Illustration: PERISCOPE IN GENERAL USE.]
[Illustration: THE UNIVERSAL OBSERVATION LENS.]
This improved periscope is applicable not only to submarine boats but
for other purposes as well, such as photographic land surface work, in
which the entire surroundings may be recorded in a single photograph.
The accompanying photograph, taken through a periscope of this type,
shows the advantages of this arrangement and gives an idea of its value
to the submarine observer when using the low-powered eyepiece. Of
course, by using the other eyepiece any particular part of the view may
be enlarged and examined in detail.
[Illustration: INSIDE OF A MINE-PLANTING SUBMARINE