n achromatic 3 1/4 inches diameter, its focal length
being 30 inches. The outer lens is a meniscus--that is bounded by a
concave and convex spherical surface which meet--having a focal length
of 18 inches. For every distant view, the aperture in front is
contracted by a diaphram to 1/8 of an inch. By this means the light is
reflected with considerable intensity and the clearness and correctness
of the pictures are truly surprising.

THE AMERICA instruments are constructed on the same principle and many
of them are equally perfect. Mr. Edward Anthony of 205 Broadway, New
York city, has constructed, and sold cameras fully equal to the German
and for which Voitlander instruments have been refused in exchange by
the purchaser.

The ordinary camera box (see fig. 5, a) varies in size to suit the
tube, and is termed medium, half, or whole. Within the box is a slide
to assist in regulating the focus, and in enlarging or diminishing the
picture. In one end of this slide is a springed groove into which the
ground-glass spectrum (g fig. 5) is slid, for the purpose of more
conveniently arranging the focus. After the plate is prepared it is
placed in the holder--partly seen at e, fig. 5, and covered with the
dark slide f, fig. 5; the spectrum is then withdrawn and the holder
takes its place, and the lids d, d, are closed after removing the dark
slide f. The plate is now ready to receive the image, and the cap c
may be removed to admit the light into the box.

A camera constructed by Voitlander is thus described by Mr. Fisher.
"It is made entirely of brass, so that variations of climate has no
effect upon it. It is very portable and when packed in its box, with
all the necessary apparatus and materials for practising the
Daguerreotype art, occupies but very little space. It is not, however,
well adapted for the Calotype process."

[Illustration: Fig. 7 (hipho_7.gif)]

"The brass foot A (fig. 7.), is placed on a table, or other firm
support, and the pillar B. screwed into it; the body of the camera, C,
C is laid into the double forked bearing D. D. The instrument is now
properly adjusted by means of the set screws, e, e, e, in the brass
foot, or it may be raised, lowered, or moved, by the telescope stand,
and when correct, fixed by the screw b. The landscape to be delineated
is viewed either through the small lens, g, or with the naked eye on
the ground glass plate H, the focus being adjusted by the screw I. The
optic