The Harley Binocular Microscope - Jackson Model, c. 1883
Extracted from PRACTICAL
MICROSCOPY by George Davis, 1889:
Collins' " Harley " binocular is now
constructed on the Jackson model. The base is large
and made in one piece, the limb carrying the body,
stage, substage, and mirror is in one piece also,
with a machine-planed groove from end to end. A
rackwork of six inches in length is attached to the
body so that very low power objectives can be used.
The fine adjustment is placed between the tube and
the limb. The stage is circular in form and with
concentric rotation, with a simple arrangement for
adjustment should it get out of the centre. It has a
clear aperture underneath, of three inches, when the
apparatus plate is removed, and consequently very
oblique illumination can be obtained by means of the
mirror alone.