that I have seen upon gelatine paper
was upon some foreign post that I had obtained for another purpose. The
emulsion employed was that described by Mr. J.B.B. Wellington, and this
gentleman agreed with me in attributing the superiority of the surface
obtained to the fine quality of the paper upon which the emulsion had
been coated. Some commercial samples appear to be coated upon paper of
somewhat coarse texture. This does not show when the print is enameled.

The unequal expansion of paper is a subject of interest, not only in
connection with gelatine paper for development, but with various
photographic processes. In making carbon transparencies for instance, the
gelatine film which is squeegeed against the glass necessarily takes its
dimensions from the paper to which it is attached, and if that be
expanded more in the one direction than another, the transparency is
similarly deformed; and so, of course, is any negative, enlarged or
otherwise, produced in the camera therefrom. A reproduced negative by
contact printing may either have the distortion due to expansion of the
paper bearing the gelatine film removed or doubled, according to the
direction in which the paper is used for the new negative.--_W.E.
Debenham, in Br. Jour. of Photography_.

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MEASURING THE THICKNESS OF BOILER PLATES.

An ingenious process for determining the thickness of iron plates in
boilers, or places where they cannot otherwise be measured without
cutting them, has been invented by M. Lebasteur. He spreads upon the
plate the thickness of which he desires to find, and also upon a piece of
sheet iron of known thickness, a layer of tallow about 0.01 inch thick.
He then applies to each, for the same length of time, a small object,
such as a surgeon's cauterizing instrument, heated as nearly as possible
to a constant temperature. The tallow melts, and as in the thicker plate
the heat of the cautery is conducted away more rapidly, while in the thin
plate the heat is less freely conducted away, and the tallow is
consequently melted over a large area, the diameters of the circles of
bare metal around the heated point, bounded after cooling by a little
ridge of tallow, will be to each other inversely as the thickness of the
plates. The process is stated to have given in the inventor's hands,
results of great accuracy.

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GROUPS OF STATUARY FOR THE PEDI