Blair’s fluid telescope, with an account of its performance--Barlow’s large refracting telescope with a fluid concave lens--Its construction, and the effect it produces on double stars, &c.--Rogers’ achromatic telescope on a new plan--Wilson’s telescope, &c. _page_ 269-283. 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. CHAPTER VI. MISCELLANEOUS REMARKS IN RELATION TO TELESCOPES.