the instrument to the Abbé Moigno, the distinguished author of L'Optique Moderne, to M. Soleil and his son-inlaw, M. Duboscq, the eminent Parisian opticians, and to some members of the Institute of France. These gentlemen saw at once the value of the instrument, not merely as one of amusement, but as an important auxiliary in the arts of portraiture and sculpture. M. Duboscq immediately began to make the lenticular stereoscope for sale, and executed a series of the most beautiful binocular Daguerreotypes of living individuals, statues, bouquets of flowers, and objects of natural history, which thousands of individuals flocked to examine and admire. In an interesting article in La Presse,1 the Abbé Moigno gave the following account of the introduction of the instrument into Paris :—

"In his last visit to Paris, Sir David Brewster intrusted the models of his stereoscope to M. Jules Duboscq, son-inlaw and successor of M. Soleil, and whose intelligence, activity, and affability will extend the reputation of the distinguished artists of the Rue de l'Odeon, 35. M. Jules Duboscq has set himself to work with indefatigable ardour. Without requiring to have recourse to the binocular camera, he has, with the ordinary Daguerreotype apparatus, procured a great number of dissimilar pictures of statues, basreliefs, and portraits of celebrated individuals, &c. His stereoscopes are constructed with more elegance, and even with more perfection, than the original English (Scotch) instruments, and while he is shewing their wonderful effects to natural philosophers and amateurs who have flocked to him in crowds, there is a spontaneous and unanimous cry of admiration."

1 December 28, 1550.

While the lenticular stereoscope was thus exciting much interest in Paris, not a single instrument had been made in London, and it was not till a year after its introduction into France that it was exhibited in England. In the fine collection of philosophical instruments which M. Duboscq contributed to the Great Exhibition of 1851, and for which he was honoured with a Council medal, he placed a lenticular stereoscope, with a beautiful set of binocular Daguerreotypes. This instrument attracted the particular attention of the Queen, and before the closing of the Crystal Palace, M. Duboscq executed a beautiful stereoscope, which I presented to Her Majesty in his name. In consequence of this public exhibition of the instrument, M. Duboscq received several orders from England, and a large number of stereoscopes were thus introduced into this country. The demand, however, became so great, that opticians of all kinds devoted themselves to the manufacture of the instrument, and photographers, both in Daguerreotype and Talbotype, found it a most lucrative branch of their profession, to take binocular portraits of views to be thrown into relief by the stereoscope. Its application to sculpture, which I had pointed out, was first made in France, and an artist in Paris actually copied a statue from the relievo produced by the stereoscope.

Three years after I had published a description of the lenticular stereoscope, and after it had been in general use in France and England, and the reflecting stereoscope forgotten,1 Mr. Wheatstone printed, in the Philosophical Transactions for 1852, a paper on Vision, in which he says

1 "Le fait est," says the Abbé Moigno, "que le stéréoscope par réflexion était presque complètement oublié, lorsque Sir David Brewster construisit son stéréoscope par refraction que nous allons décrire."-Cosmos, vol. i. p. 4, 1852.

"1

that he had previously used "an apparatus in which prisms were employed to deflect the rays of light proceeding from the pictures, so as to make them appear to occupy the same place;" and he adds, "I have called it the refracting stereoscope. Now, whatever Mr. Wheatstone may have done with prisms, and at whatever time he may have done it, I was the first person who published a description of stereoscopes both with refracting and reflecting prisms; and during the three years that elapsed after he had read my paper, he made no claim to the suggestion of prisms till after the great success of the lenticular stereoscope. The reason why he then made the claim, and the only reason why we do not make him a present of the suggestion, will appear from the following history :

In the paper above referred to, Mr. Wheatstone says,— "I recommend, as a convenient arrangement of the refracting stereoscope for viewing Daguerreotypes of small dimensions, the instrument represented, (Fig. 4,) shortened in its length from 8 inches to 5, and lenses 5 inches focal distance, placed before and close to the prisms."2 Although this refracting apparatus, which is simply a deterioration of the lenticular stereoscope, is recommended by Mr. Wheatstone, nobody either makes it or uses it. The semi-lenses or quarterlenses of the lenticular stereoscope include a virtual and absolutely perfect prism, and, what is of far more consequence, each lens is a variable lenticular prism, so that, when the eye-tubes are placed at different distances, the lenses have different powers of displacing the pictures. They can thus unite pictures placed at different distances, which cannot be done by any combination of whole lenses and prisms. 2 Ibid., pp. 9, 10.

1 Phil. Trans., 1852, p. 6.

In the autumn of 1854, after all the facts about the stereoscope were before the public, and Mr. Wheatstone in full possession of all the merit of having anticipated Mr. Elliot in the publication of his stereoscopic apparatus, and of his explanation of the theory of stereoscopic relief, such as it was, he thought it proper to revive the controversy by transmitting to the Abbé Moigno, for publication in Cosmos, an extract of a letter of mine dated 27th September 1838. This extract was published in the Cosmos of the 15th August 1854,1 with the following illogical commentary by the editor.

"Nous avons eu tort mille fois d'accorder à notre illustre ami, Sir David Brewster, l'invention du stéréoscope par réfraction. M. Wheatstone, en effet, a mis entre nos mains une lettre datée, le croirait on, du 27 Septembre 1838, dans lequel nous avons lû ces mots écrits par l'illustre savant Ecossais : 'I have also stated that you promised to order for me your stereoscope, both with reflectors and PRISMS. J'ai aussi dit (à Lord Rosse 2) que vous aviez promis de commander pour moi votre stéréoscope, celui avec réflecteurs et celui avec prismes.' Le stéréoscope par réfraction est donc, aussi bien que le stéréoscope par réflexion, le stéréoscope de M. Wheatstone, qui l'avait inventé en 1838, et le faisait construire à cette époque pour Sir David Brewster lui-même. Ce que Sir David Brewster a imaginée, et c'est une idée très ingénieuse, dont M. Wheatstone ne lui disputât jamais la gloire, c'est de former les deux prismes du stéréoscope par réfraction avec les deux moitiés d'une même lentille."

That the reader may form a correct idea of the conduct of Mr. Wheatstone in making this claim indirectly, and in

1 Vol. v. livre viii. p. 241.

2 Mr. Andrew Ross, the celebrated optician!

C

His

a foreign journal, whose editor he has willingly misled, I must remind him that I first saw the reflecting stereoscope at the meeting of the British Association at Newcastle, in the middle of August 1838. It is proved by my letter that he and I then conversed on the subject of prisms, which at that time he had never thought of. I suggested prisms for displacing the pictures, and Mr. Wheatstone's natural reply was, that they must be achromatic prisms. This fact, if denied, may be proved by various circumstances. paper of 1838 contains no reference to prisms. If he had suggested the use of prisms in August 1838, he would have inserted his suggestion in that paper, which was then unpublished; and if he had only once tried a prism stereoscope, he never would have used another. On my return to Scotland, I ordered from Mr. Andrew Ross one of the reflecting stereoscopes, and one made with achromatic prisms; but my words do not imply that Mr. Wheatstone was the first person who suggested prisms, and still less that he ever made or used a stereoscope with prisms. But however this may be, it is a most extraordinary statement, which he allows the Abbé Moigno to make, and which, though made a year and a half ago, he has not enabled the Abbé to correct, that a stereoscope with prisms was made for me (or for any other person) by Mr. Ross. I never saw such an instrument, or heard of its being constructed: I supposed that after our conversation Mr. Wheatstone might have tried achromatic prisms, and in 1848, when I described my single prism stereoscope, I stated what I now find is not correct, that I believed Mr. Wheatstone had used two achromatic prisms. The following letter from Mr. Andrew Ross will prove the main fact that he never constructed