LETTER I.

Extent and interest of the subject—Science employed by ancient governments to deceive and enslave their subjects—Influence of the supernatural upon ignorant minds—Means employed by the ancient magicians to establish their authority—Derived from a knowledge of the phenomena of Nature—From the influence of narcotic drugs upon the victims of their delusion—From every branch of science—Acoustics—Hydrostatics—Mechanics—Optics—M. Salverte’s work on the occult sciences—Object of the following letters

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LETTER II.

The eye the most important of our organs—Popular description of it—The eye is the most fertile source of mental illusions—Disappearance of objects when their images fall upon the base of the optic nerve—Disappearance of objects when seen obliquely—Deceptions arising from viewing objects in a faint light—Luminous figures created by pressure on the eye, either from external causes or from the fulness of the blood-vessels—Ocular spectra or accidental colours—Remarkable effects produced by intense light—Influence of the imagination in viewing these spectra—Remarkable illusion produced by this affection of the eye—Duration of impressions of light on the eye—Thaumatrope—Improvements upon it suggested—Disappearance of halves of objects or of one of two persons—Insensibility of the eye to particular colours—Remarkable optical illusion described

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LETTER III.

Subject of spectral illusions—Recent and interesting case of Mrs. A.—Her first illusion affecting the ear—Spectral apparition of her husband—Spectral apparition of a cat—Apparition of a near and living relation in grave-clothes, seen in a looking-glass—Other illusions, affecting the ear—Spectre of a deceased friend sitting in an easy-chair—Spectre of a coach-and-four filled with skeletons—Accuracy and value of the preceding cases—State of health under which they arose—Spectral apparitions are pictures on the retina—The ideas of memory and imagination are also pictures on the retina—General views of the subject—Approximate explanation of spectral apparitions

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LETTER IV.

Science used as an instrument of imposture—Deceptions with plane and concave mirrors practised by the ancients—The magician’s mirror—Effects of concave mirrors—AËrial images—Images on smoke—Combination of mirrors for producing pictures from living objects—The mysterious dagger—Ancient miracles with concave mirrors—Modern necromancy with them, as seen by Cellini—Description and effects of the magic lantern—Improvements upon it—Phantasmagoric exhibitions of Philipstall and others—Dr. Young’s arrangement of lenses, &c., for the Phantasmagoria—Improvements suggested—Catadioptrical phantasmagoria for producing the pictures from living objects—Method of cutting off parts of the figures—Kircher’s mysterious hand-writing on the wall—His hollow cylindrical mirror for aËrial images—Cylindrical mirror for re-forming distorted pictures—Mirrors of variable curvature for producing caricatures

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LETTER V.

Miscellaneous optical illusions—Conversions of cameos into intaglios, or elevations into depressions, and the reverse—Explanation of this class of deceptions—Singular effects of illumination with light of one simple colour—Lamps for producing homogeneous yellow light—Methods of increasing the effects of this exhibition—Method of reading the inscription of coins in the dark—Art of deciphering the effaced inscription of coins—Explanation of these singular effects—Apparent motion of the eyes in portraits—Remarkable examples of this—Apparent motion of the features of a portrait, when the eyes are made to move—Remarkable experiment of breathing light and darkness

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LETTER VI.

Natural phenomena marked with the marvellous—Spectre of the Brocken described—Analogous phenomena—AËrial spectres seen in Cumberland—Fata Morgana in the Straits of Messina—Objects below the horizon raised and magnified by refraction—Singular example seen at Hastings—Dover Castle seen through the hill on which it stands—Erect and inverted images of distant ships seen in the air—Similar phenomena seen in the Arctic regions—Enchanted coast—Mr. Scoresby recognizes his father’s ship by its aËrial image—Images of cows seen in the air—Inverted images of horses seen in South America—Lateral images produced by refraction—AËrial spectres by reflexion—Explanation of the preceding phenomena

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LETTER VII.

Illusions depending on the ear—Practised by the ancients—Speaking and singing heads of the ancients—Exhibition of the Invisible Girl described and explained—Illusions arising from the difficulty of determining the direction of sounds—Singular example of this illusion—Nature of ventriloquism—Exhibitions of some of the most celebrated ventriloquists—M. St. Gille—Louis Brabant—M. Alexandre—Capt. Lyon’s account of Esquimaux ventriloquists

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LETTER VIII.

Musical and harmonic sounds explained—Power of breaking glasses with the voice—Musical sounds from the vibration of a column of air—and of solid bodies—Kaleidophone—Singular acoustic figures produced on sand laid on vibrating plates of glass—and on stretched membranes—Vibration of flat rulers and cylinders of glass—Production of silence from two sounds—Production of darkness from two lights—Explanation of these singular effects—Acoustic automaton—Droz’s bleating sheep—Maillardet’s singing-bird—Vaucanson’s flute-player—His pipe and tabor-player—Baron Kempelen’s talking-engine—Kratzenstein’s speaking-machine—Mr. Willis’s researches

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LETTER IX.

Singular effects in nature depending on sound—Permanent character of speech—Influence of great elevations on the character of sounds, and on the powers of speech—Power of sound in throwing down buildings—Dog killed by sound—Sounds greatly changed under particular circumstances—Great audibility of sounds during the night explained—Sounds deadened in media of different densities—Illustrated in the case of a glass of champagne—and in that of new-fallen snow—Remarkable echoes—Reverberations of thunder—Subterranean noises—Remarkable one at the Solfaterra—Echo at the Menai suspension bridge—Temporary deafness produced in diving-bells—Inaudibility of particular sounds to particular ears—Vocal powers of the statue of Memnon—Sounds in granite rocks—Musical mountain of El-Nakous

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LETTER X.

Mechanical inventions of the ancients few in number—Ancient and modern feats of strength—Feats of Eckeberg particularly described—General explanation of them—Real feats of strength performed by Thomas Topham—Remarkable power of lifting heavy persons when the lungs are inflated—Belzoni’s feat of sustaining pyramids of men—Deception of walking along the ceiling in an inverted position—Pneumatic apparatus in the foot of the house-fly for enabling it to walk in opposition to gravity—Description of the analogous apparatus employed by the gecko lizard for the same purpose—Apparatus used by the Echineis remora, or sucking-fish

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LETTER XI.

Mechanical automata of the ancients—Moving tripods—Automata of DÆdalus—Wooden pigeon of Archytas—Automatic clock of Charlemagne—Automata made by Turrianus for Charles V.—Camus’s automatic carriage made for Louis XIV.—Degenne’s mechanical peacock—Vaucanson’s duck which ate and digested its food—Du Moulin’s automata—Baron Kempelen’s automaton chess-player—Drawing and writing automata—Maillardet’s conjurer—Benefits derived from the passion for automata—Examples of wonderful machinery for useful purposes—Duncan’s tambouring machinery—Watt’s statue-turning machinery—Babbage’s calculating machinery

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LETTER XII.

Wonders of chemistry—Origin, progress, and objects of alchemy—Art of breathing fire—Employed by Barchochebas, Eunus, &c.—Modern method—Art of walking upon burning coals and red-hot iron, and of plunging the hands in melted lead and boiling water—Singular property of boiling tar—Workmen plunge their hands in melted copper—Trial of ordeal by fire—Aldini’s incombustible dresses—Examples of their wonderful power in resisting flame—Power of breathing and enduring air of high temperatures—Experiments made by Sir Joseph Banks, Sir Charles Blagden, and Mr. Chantrey

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LETTER XIII.

Spontaneous combustion—In the absorption of air by powdered charcoal—and of hydrogen by spongy platinum—Dobereiner’s lamp—Spontaneous combustion in the bowels of the earth—Burning cliffs—Burning soil—Combustion without flame—Spontaneous combustion of human beings—Countess Zangari—Grace Pett—Natural fire-temples of the Guebres—Spontaneous fires in the Caspian Sea—Springs of inflammable gas near Glasgow—Natural light-house of Maracaybo—New elastic fluids in the cavities—of gems—Chemical operations going on in their cavities—Explosions produced in them by heat—Remarkable changes of colour from chemical causes—Effects of the nitrous oxide or Paradise gas when breathed—Remarkable cases described—Conclusion

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