al part of the instrument consist of the small set of achromatic
lenses already described. When the portrait or view is deliniated on
the ground glass to the entire satisfaction of the operator, the brass
cap L is placed over the lens, and the entire body is removed away into
the dark, taking care not to disturb the position of the stand. The
body is now detached at the part H, and the prepared paper or plate
enclosed in the brass frame work introduced in its place; the whole is
again placed upon the pedestal, the brass cap L is removed, by which
the paper or plate is exposed to the full influence of the light, after
which the cap is again replaced.

Mr. Woodbridge, of this city, has constructed an instrument for taking
full length portraits on plates 10 by 13 inches, which is worthy of
some notice. It is a double camera, consisting of two boxes, placed in
a frame, one above the other, and so arranged as to slide easily up and
down. After the focus has been adjusted, on the object, in both
cameras, the plate is put into the upper box, in the manner already
described, until the superior portion of the figure is complete; it is
then placed in the second box and the lower extremities obtained. The
adjustment of the instrument is so complete that a perfect union of the
parts is effected in the picture without the least possible line of
demarkation being visible. Fig. 8 gives a front view of this
instrument.

[Illustration: Fig. 8 (hipho_8.gif)]

Fig. 9 represents Talbot's Calotype Camera,--a very beautiful
instrument.

The copying camera box has an extra slide in the back end, by which it
may be considerably lengthened at pleasure.

II.--CAMERA STAND.--The best constructed stands are made of maple or
black walnut wood, having a cast iron socket (a, Fig. 12,) through
which the sliding rod b passes, and into which the legs c, c, with iron
screw ferules are inserted. The platform d is made of two pieces,
hinged together, as at e, and having a thumb screw for the purpose of
elevating or depressing the instrument.

[Illustration: Fig. 9 (hipho_9.gif)]

III. MERCURY BATH.--Fig. 13 gives a front view of the mercury bath now
in general use in this country for mercurializing and bringing out the
picture. It is quite an improvement on those first used. To make it
more portable it is in three pieces, a b and c; having a groove e on
one side to receive the thermometre tube and scale by which the proper
degree of heati