Thomas
Rubergall, mathematical, optical,
and philosphical instrument maker, was active
from 1802-1854 at various addresses in
London. In 1802, he traded at 27 Piccadilly,
Princes Street, Soho, in 1805-1823, he
was located at 27 Coventry Street, and in
1826-1854, he was located at 24 Coventry Street,
Haymarket.
The Gould type microscope
is described and illustrated in the book Microscope
Manipulation by George T. Fisher, 1845 as
follows:
Gould's
Microscope. A very convenient and powerful
form of instrument is that which bears the above name.
Its general form is as in the annexed diagram, and the
whole fits into a mahogany box. In the centre of the
lid of the box screws the upright square stem A, fig.
14. This has upon one side of it a rack movement, in
which works the screw B, intended to raise or depress
the stage C, as occasion requires. C consists of two
plates of brass held together by a spring; between
these plates the object slider D is placed. E is an arm
at right angles to A; it is attached and confined by
the screw at the end of it in A. F must be supposed to
represent three lenses, or magnifiers, screwed
together, the focus of each being such that they act in
unison together. G is a reflector to cast the light
upwards through the object to the eye. H is the main
tube, which bears the eye-lens at one end, and screws
upon one of the object lenses at the other.
When the instrument is in
use, the focus is adjusted by moving the screw B, and
the degree of magnifying power is according to the
lenses, which are screwed on to the bottom of H. Thus,
if one lens obtain an increase of 10, two lenses may
obtain a power of 100, and three lenses of 1000. Let it
be always remarked, that the more lenses the more
obscure will be the image.