CHAPTER V.
ON REFLECTING TELESCOPES.
SECT. 1.--HISTORY OF THE INVENTION, AND A GENERAL DESCRIPTION OF THE CONSTRUCTION OF THESE INSTRUMENTS.
Gregory’s Reflector--Newtonian Reflector--Cassegrainian Reflector--Magnifying powers of reflectors--Short’s Reflectors--Their powers and prices--_General remarks on Gregorian reflectors_--Apertures and magnifying powers of Newtonian telescopes--_Prices_ of Reflecting telescopes
_page_ 284-301.
SECT. 2.--THE HERSCHELIAN TELESCOPE.
Description of Sir W. Herschel’s 40 feet telescope, with its machinery, apparatus, and the discoveries made by it--Sir J. Herschel’s 20 feet reflector _page_ 301-308.
SECT. 3.--RAMAGE’S LARGE REFLECTING TELESCOPE.
_page_ 308-311.
SECT. 4.--THE AERIAL REFLECTOR--CONSTRUCTED BY THE AUTHOR.
Construction of this telescope, and the manner of using it--Illustrated by figures--Its properties and advantages--Tube not necessary in reflecting telescopes--How a large reflector might be constructed without a tube--How the form of a telescope may be used for viewing perspectives
_page_ 311-325.
SECT. 4.--EARL OF ROSSE’S REFLECTING TELESCOPES.
His mode of forming a large speculum, &c., see also, Appendix
_page_ 325-328.
SECT. 5.--REFLECTING TELESCOPES WITH GLASS SPECULA.
Various experiments on this subject, with their results
_page_ 329-331.
SECT. 6.--A REFLECTING TELESCOPE WITH A SINGLE MIRROR AND NO EYE-PIECE.
Experiments illustrative of this construction
_page_ 332-334.
ON THE EYE-PIECES OF TELESCOPES. ASTRONOMICAL EYE-PIECES.
Huygenian eye-piece--Ramsden’s eye-piece--Aberration of lenses--Celestial eye-pieces with variable powers. _Diagonal_ eye-pieces--Various forms of them described--Various aspects in which objects may be viewed by them
_page_ 335-347.
TERRESTRIAL EYE-PIECES.
Eye-pieces with four lenses--Proportions of the focal lengths of these lenses--Dimensions and powers of several eye-pieces stated
_page_ 347-353.
DESCRIPTION OF AN EYE-PIECE, &C., OF AN OLD DUTCH ACHROMATIC TELESCOPE.
This telescope supposed to have been _invented_ in Holland before Dollond’s discovery was known--Peculiarity of its eye-piece
_page_ 354-357.
DESCRIPTION OF THE PANCRATIC EYE-TUBE.
_page_ 357-360.