Appendix
Reports of Committees of the Franklin Institute
Report on Amasa Holcomb’s Reflecting Telescope.
[From Journal of the Franklin Institute, July 1834, new ser. vol. 14 (whole no. 18), pp. 169-172.]
The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania for the promotion of the Mechanic Arts, to whom was referred for examination a Reflecting Telescope, manufactured by Mr. Amasa Holcomb, of Southwick, Hampden county, Massachusetts,
REPORT:—
That the following is the description of the instrument as given by Mr. Holcomb.
“The telescope submitted to the examination of the Committee of the Franklin Institute is of the reflecting kind; has a focal length of six feet; the diameter of the speculum is three inches nine-tenths; the rays of light are reflected but once; the image formed in the focus of the speculum is viewed by a common astronomical eye piece, or by a single lens; it has also an eye piece for viewing land objects, which shows them erect. The telescope is of the same construction as those of Sir William Herschell, the observer having his back towards the object and looking directly towards the speculum. It has an advantage over those of the Gregorian and Newtonian forms, by showing the object brighter with the same aperture, there being no light lost by a second reflection. The diameter of the speculum is small in proportion to the length of the instrument; it will bear a diameter of eight inches, with much advantage for viewing very small stars, in consequence of the great increase of the light.
The magnifying powers that are used are, forty, ninety, and two hundred and fifty.”