Colours, the beauty of nature--Opinions which were formerly entertained respecting their cause--Sir I. Newton’s experiments with the Prism--Colours and phenomena produced by the prism--Imperfection of optic lenses--Various illustrations--Differently coloured rays have not the same illuminating power--Heating and chemical properties of some of the rays of the solar spectrum--property of communicating the Magnetic power--Fraunhofer, and his discoveries in reference to the spectrum--Experiments on white and coloured light _page_ 123-137. SECT. 2.--ON THE COLOURS OF NATURAL OBJECTS. Colours not in the objects themselves, but in the light which falls upon them--Illustrations of this position--Atmosphere the source of a variety of colours--Various natural phenomena, in relation to colour, explained _page_ 137-143. SECT. 3.--PHENOMENA OF THE RAINBOW. Rainbow described--Experiments to illustrate its cause--Descriptions of its various phenomena, and optical explanations of their causes--Rainbows exhibiting _complete circles_--Their appearance in different countries--Summary view of the principal facts respecting the rainbow--_Lunar_ rainbows--Scriptural allusions to the rainbow--Whether there was any rainbow before the deluge _page_ 144-157. SECT. 4.--REFLECTIONS ON THE BEAUTY AND UTILITY OF COLOURS. Beauty and variety derived from colours in the scenery of nature--Colours produced by the atmosphere in different countries--What would be the aspect of nature, in heaven and on earth, were there only one colour--How it would affect the common intercourse and employments of society--Wisdom and Beneficence of the Creator displayed in the diversity of colours--Throughout all the systems of the universe, a diversity of colours prevails--This subject has a tendency to inspire us with gratitude _page_ 158-168. PART II. ON TELESCOPES. CHAPTER I. HISTORY OF THE INVENTION OF TELESCOPES. 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 _page_ 169-183. CHAPTER II. OF THE CAMERA OBSCURA. 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 _page_ 184-196. THE DAGUERREOTYPE.