The telescope a noble instrument--Effects it produces--Whether known to the ancients--Friar Bacon’s ideas respecting telescopes--First constructed in Holland--The invention claimed by different persons--Galileo’s account of the construction of his telescope--Discoveries which he made with this instrument--How his discoveries were received by the learned--Specimens of learned nonsense brought forward by pretended philosophers--Supposed length of Galileo’s telescope--Various claimants to the invention of this instrument
Appearance of objects in a camera obscura--The dark chamber--This instrument serves to explain the nature of a refracting telescope--Particulars to be attended to, in exhibiting objects with the Camera--It illustrates the nature of vision--Revolving camera obscura--_Portable_ camera
An important discovery for fixing the images produced by the camera--Description of the Daguerreotype process--Preparation of the plate, fixing the impression, &c.--Preparation of photogenic paper--Beneficial effects which this art may produce--Representations of objects in the heavens, &c.
ON THE OPTICAL ANGLE, AND THE APPARENT MAGNITUDE OF OBJECTS.
Various illustrations of the apparent magnitude of objects--Fallacies in relation to apparent magnitudes--Apparent magnitudes in the heavens--Difference between _absolute_ and apparent magnitudes
ON THE DIFFERENT KINDS OF REFRACTING TELESCOPES.
Construction and peculiar properties of this instrument
SECT. 2.--THE COMMON ASTRONOMICAL REFRACTING TELESCOPE.
Description of its nature and construction--How its magnifying power is determined. Table of the linear aperture, magnifying powers, &c., of astronomical telescopes from 1 to 120 feet in length--Summary view of the properties of this telescope
This telescope is used without a tube--Description of the apparatus connected with it, illustrated with figures--Huygens’ Hartsocker’s and Cassini’s large telescopes
SECT. 4.--THE COMMON REFRACTING TELESCOPE FOR TERRESTRIAL OBJECTS.
Arrangement of its lenses--Magnifying power--Manner in which the rays of light are refracted through the telescopes now described
SECT. 5.--TELESCOPE FORMED BY A SINGLE LENS.
Various experiments in relation to this point--Experiments with a lens 26 focal distance, and 11-1/2 inches diameter