CONTENTS.

[PART I.]
[ON LIGHT.]
[INTRODUCTION.]
Necessity of light to the knowledge and happiness of all sentient beings—Its beautiful and enlivening effects—An emblem of the Deity—Provision made for its universal diffusion page 1-7.
[CHAPTER I.]
[General Properties of Light.]
Interesting nature of this study—Different hypotheses which have been formed respecting the nature of light—It radiates in straight lines—Moves with amazing velocity—Flows in all directions from luminous bodies—Duration of its impressions on the eye—Supposed to have a certain degree of force or momentum—Experiments in relation to this point—Its intensity diminished in proportion to the square of the distance—Its reflection from opake bodies renders objects visible—Intensity of reflected light—Subject to the law of attraction—Forms a constituent part of certain bodies—Solar phosphori, and the phenomena they exhibit—Produces certain effects on planets and flowers, exemplified in a variety of instances—Supposed to have an influence on the propagation of sound page 8-37
[Reflections on the nature of light], and the multifarious effects it produces throughout the universe—A representation of the Divinity—Wisdom and Goodness of God displayed in its formation page 37-40.
[CHAPTER II.]
[On the Refraction of Light.]
Nature of refraction—Illustrated by experiments—Angle of refraction—Familiar experiments illustrative of refraction—Refraction explains the causes of many curious and interesting phenomena—Its effect on the heavenly bodies—On the twilight—Illustrated by figures
page 41-53.
[EXTRAORDINARY CASES OF REFRACTION IN RELATION TO TERRESTRIAL OBJECTS.]
Extraordinary appearance of the coast of France from Hastings—Appearance of a ship seen by Captain Colby, beyond the coast of Caithness—Scoresby’s view of his father’s ship when beyond the horizon—Phenomenon near the Himalaya mountains—Bell Rock light-house—Summary statement of the diversified effects of refraction—Reflections on the beneficent and diversified effects produced by the law of refraction—It increases the length of the day, particularly in the polar regions—Is the cause of that splendour which appears in the objects around us—Quantity of refraction in respect to terrestrial objects, and its utility—Its effects may be more diversified in other worlds
page 53-63.
[CHAPTER III.]
[On the Refraction of Light through Spherical Transparent Substances, or Lenses.]
Refraction the foundation of optical instruments—Various forms of lenses—Parallel, converging, and diverging rays—Illustrated by diagrams—Concave lenses, their effects, and how to find their focal distances—Images formed by convex lenses—Illustrated by experiments—Principles in relation to images formed by lenses—Their magnifying powers, &c. page 63-75.
[REFLECTIONS DEDUCED FROM THE PRECEDING SUBJECT.]
Property of the rays of light in forming images of objects—Wonderful results and discoveries which have flowed from this property—in relation to our knowledge of the scenery of the heavens and the minute parts of nature—and of our views of the attributes of Deity page 75-80.
[CHAPTER IV.]
[On the Reflection of Light.]
Nature of reflection—Plane, convex, and concave speculums—Angle of reflection—Reflection of objects from plane mirrors, illustrated by figures—Reflection by Convex and Concave mirrors—Properties of convex mirrors, and the purposes to which they are applied. Properties of concave speculums, and their utility—Of the images formed by concave speculums—Illustrated by a variety of figures and experiments—Their power of magnifying and burning—Amusing deceptions produced by—Resemblance between the properties of convex lenses, and concave mirrors—Quantity of light reflected by polished surfaces page 81-106.
[UNCOMMON APPEARANCES OF NATURE PRODUCED BY THE COMBINED INFLUENCE OF REFLECTION AND REFRACTION.]
Fata Morgana—The Mirage—Inverted images of ships seen in the horizon—Appearance of Dover castle at Ramsgate—Spectre of the Brocken—Scenes in the Highlands of Scotland—Large cross seen at Migné in France—Dr. Wollaston’s illustrations of such phenomena—Utility of science in dissipating superstitious fears page 106-118.
[REMARKS AND REFLECTIONS IN REFERENCE TO THE PHENOMENA DESCRIBED ABOVE.]
Light, the beauty of the universe, and a symbol of the Divinity—In other worlds it may produce an infinite variety of sublime scenery page 118-122.
[CHAPTER V.]
[Sect. 1.—On the Colours of Light.]
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.]
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. page 196-205.
[CHAPTER III.]
[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 page 206-213.
[CHAPTER IV.]
[On the Different Kinds of Refracting Telescopes.]
[Sect. 1.—The Galilean Telescope.]
Construction and peculiar properties of this instrument page 214-217.
[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 page 218-224.
[Sect. 3.—The Aerial 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 page 224-228.
[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 page 228-231.
[Sect. 5.—Telescope Formed by a Single Lens.]
Various experiments in relation to this point—Experiments with a lens 26 focal distance, and 11½ inches diameter page 232-235.
[Sect. 6.—The Achromatic Telescope.]
Imperfections of common refracting telescopes—Dollond’s discovery—Newton’s error—Explanation of the principle of achromatic telescopes—Combination of lenses—Difficulties in the construction of such instruments—Difficulty in procuring large disks of flint glass—Guinaud’s experiments page 235-248.
[NOTICES OF SOME LARGE ACHROMATIC TELESCOPES ON THE CONTINENT, AND IN GREAT BRITAIN.]
The Dorpat telescope—Sir J. South’s telescope—Captain Smyth’s—Rev. Dr. Pearson’s—Mr. Lawson’s—Mr. Cooper’s—Mr. Bridges’, &c.,—Achromatics in Cambridge and Paris observatories pages 248-254.
[ACHROMATIC TELESCOPES OF A MODERATE SIZE, WITH THEIR PRICES, AS SOLD BY LONDON OPTICIANS.]
The 2½ feet Achromatic—The 3½ feet—The powers applied to it—and the views it gives of the heavenly bodies—The 5 feet achromatic—Stands for telescopes, illustrated by engravings page 254-264.
[PROPORTIONS OR CURVATURE OF THE LENSES WHICH FORM AN ACHROMATIC OBJECT-GLASS.]
Various tables and explanations page 265-269.
[ACHROMATIC TELESCOPES COMPOSED OF FLUID LENSES.]
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.]
1. Adjustments requisite to be attended to in the use of telescopes—2. State of the atmosphere most proper for observing terrestrial and celestial objects—Average number of hours in the year fit for celestial observations.—3. On the magnifying powers requisite for observing the phenomena of the different planets—Comets—Double stars, &c.—Illustrated at large from p. 369-380.—4. Mode of exhibiting the solar spots—Eye-pieces best adapted for this purpose—How they may be exhibited to a large company—Mode in which their dimensions may be determined.—5. On the space-penetrating power of telescopes—Herschel’s observations on space-penetrating powers—Comparison of achromatic and Gregorian reflectors.—6. On choosing telescopes, and ascertaining their properties—Various modes of ascertaining the goodness of telescopes—General remarks and cautions on this point—A circumstance which requires to be attended to in using achromatics.—7. On the mode of determining the magnifying power of telescopes—Various experiments in relation to this point.—8. On cleaning the lenses of telescopes page 361-407.
[ON MEGALASCOPES, OR TELESCOPES FOR VIEWING VERY NEAR OBJECTS.]
Mode of adapting a telescope for this purpose—objects to which they may be applied page 407-411.
[REFLECTIONS ON LIGHT AND VISION, AND ON THE NATURE AND UTILITY OF TELESCOPES.]
Wonderful and mysterious nature of light—The organ of vision, and its expansive range—Wonderful nature of the telescope, and the objects it has disclosed to view—No boundaries should be set to the discoveries of science and the improvement of art—The telescope is a machine which virtually transports us to the distant regions of space—It enlarges our views of the sublime scenes of creation—It has tended to amplify our conceptions of the empire and the attributes of the Deity—Various uses of this instrument in relation to science and common life page 411-431.
[CHAPTER VII.]
[On the Method of Grinding and Polishing Optical Lenses and Specula.]
1. Directions for grinding lenses for eye-glasses, microscopes, &c.—2. Method of casting and grinding the specula of reflecting telescopes—Compositions for speculum metal—To try the figure of the metal—To adjust the eye-hole of Gregorian reflectors—To center the specula—To center lenses. page 432-442.
[PART III.]
[ON VARIOUS ASTRONOMICAL INSTRUMENTS.]
[CHAPTER I.]
[On Micrometers.]
Various descriptions of micrometers—Cavallo’s micrometer described—To ascertain the value of its divisions—Practical uses of this micrometer—Problems which may be solved by it—Tables for facilitating its use page 443-452.
[CHAPTER II.]
[On the Equatorial Telescope, or Portable Observatory.]
History of equatorials—Description of one of the simplest construction of these instruments—To adjust the equatorial for observation—To adjust the line of sight—Description of the nonius—To find the meridian line by one observation—Manner of observing stars and planets in the day-time page 453-464.
[OBSERVATIONS, BY THE AUTHOR, ON THE FIXED STARS AND PLANETS, MADE IN THE DAY-TIME, BY THE EQUATORIAL.]
Object of these observations—stars of the first and second magnitudes—General deductions from these observations page 464-469.
[OBSERVATIONS ON THE PLANETS IN THE DAY-TIME.]
Series of observations on Venus, when near the sun—Seen at the time of her superior conjunction in 1843—Conclusions deduced from these observations—phenomena observed during these observations—Remarkable phenomenon during an eclipse of the sun page 469-480.
[OBSERVATIONS ON JUPITER AND OTHER PLANETS.]
General conclusions, &c. page 480-485.
[UTILITY OF CELESTIAL DAY OBSERVATIONS.] page 485-491.
[ON THE ASTRONOMICAL QUADRANT.] page 492-496.
[THE ASTRONOMICAL CIRCLE.] page 496-502.
[THE TRANSIT INSTRUMENT.] page 502-505.
[CHAPTER III.]
[On Observatories.]
Leading features of a spot adapted for celestial observations—Public and private observatories—Greenwich observatory—Instruments with which an observatory should be furnished—The Author’s private observatory—Revolving domes for observatories—Cautions to be attended to in celestial observations page 506-516.
[CHAPTER IV.]
[On Orreries or Planetariums.]
History of such machines—Sphere of Archimedes and Posidonius—Dr. Long’s Uranium—Wheel-work of the common Planetarium—Figure representing this machine—Problems which may be performed by it page 517-527.
[DR. HENDERSON’S PLANETARIUM.]
Section of its wheel-work—Number of teeth in the wheels and pinions which move the different planets—Extreme accuracy of these movements. page 527-538.
[ON THE VARIOUS OPINIONS WHICH WERE ORIGINALLY FORMED OF SATURN’S RING, ILLUSTRATED WITH 13 VIEWS.]
When and by whom its true figure was discovered. page 538-543.
[ON THE SUPPOSED DIVISION OF THE EXTERIOR RING OF SATURN.]
Kater’s, Short’s, Quetelet’s and Decuppis’s observations page 543-547.
[APPENDIX.]
[1. Description of the Earl of Rosse’s Largest Telescope.]
Composition of the speculum, and the process of casting it—Mode of grinding and polishing it—Manner in which it is filled up—Expenses incurred in its construction—Results of observations which have been made with it—Two views representing this instrument and the buildings connected with it—Sir J. South’s remarks and anticipations page 548-562.
[2. Hints to amateurs in astronomy respecting the construction of telescopes.]page 563.