1851 Great Exhibition: Official Catalogue: Class X.: A. Ross
254. Ross, A., 2 Featherstone Buildings, Holborn — Inventor and Manufacturer.
Astronomical telescope, the diameter of the object-glass is 11.5 inches, mounted on a stand, with equatorial movements and complete adjustments. The optical part wrought by Ross's improved system and machinery.
This instrument is exhibited in the Western Nave.
[The grinding of an object-glass of 11A inches in diameter to a good figure, and free from both spherical and chromatic aberration, is very difficult. The advantage of a large object-glass will be seen from the following consideration. The principal reason of the superior distinctness of a telescope over unassisted vision arises from the fact, that the pupil of the eye takes in a certain number of rays of light; but, on looking through a telescope, it takes in as many more rays in proportion as the object-glass is larger than the pupil itself, and the object appears as brilliant as it would were the pupil of the eye to be enlarged to the size of the object-glass.—J. G.]
Chemical pottery wares. Complete apparatus for distillation and condensation. Manufactured in terra cotta chemical-stone ware, to stand great heat, and lined with acid-proof glaze.
Astronomical telescope, 33 inches in diameter, mounted on an equatorial stand.
Astronomical telescope, 4 inches in diameter, mounted on a pillar and claw stand.
Improved microscopes, with new method of illumination.
Improved photographic camera obscuras.
666. Ross, A.
Bleeding instruments, as substitutes for leeches and cupping instruments, adapted to apply to any part of the body. Invented by Baron Heurteloup; manufactured by J. Scholl, Berwick-street, Soho.