that deserves serious attention before earth cables are more generally
introduced; there can, however, be little doubt that they are not nearly
so much exposed as overhead wires to disturbing influences of other
kinds, such as snow, rain, wind, etc., while they certainly do
suffer, though perhaps in a less degree, by electrical
disturbances.--_Engineering_.

* * * * *




THE PHOTOGRAPHIC IMAGE: WHAT IT IS.

[Footnote: A communication to the Sheffield Photographic Society in the
_British Journal of Photography_.]


It is quite possible that in the remarks I propose making this evening
in connection with the photographic art I may mention topics and some
details which are familiar to many present; but as chemistry and optical
and physical phenomena enter largely into the theory and practice
of photography, the field is so extensive there is always something
interesting and suggestive even in the rudiments, especially to those
who are commencing their studies. Although this paper may be considered
an introductory one, I do not wish to load it with any historical
account, or describe the early methods of producing a light picture, but
shall at once take for my subject, "The Photographic Image: What It
Is," and under this heading I must restrict myself to the collodion and
silver or wet process, leaving gelatine dry plates, collodio-chloride,