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men, should any of them on their visit to England desire to see the Theatres in London, always to go to the boxes, which are frequented by a respectable class of people, and there they will receive much civility and attention, but never for the sake of economy go either to the pit or gallery of any of them, (except the Italian Opera) because these places are always resorted to by the humbler classes, as well as by rogues, thieves, and pickpockets, and should a stranger happen to be there, he is often teased and insulted with gross and abusive language by these fellows, besides he could not see much of the performances; we state this from the treatment we once experienced at Astley's Amphitheatre, but on our discovering the error, we immediately left the place. We therefore advise our readers, always to pay a little more and go to the boxes, rather than be in company with a set of fellows, who derive pleasure at the expense of your comfort.

And here we would inform our countrymen that the majority of the lower orders in England are very rude in their manners and behaviour towards strangers, whom they do not like to see in their own country.

CHAPTER XI.

SCIENTIFIC INSTITUTIONS.

THE GALLERY OF PRACTICAL SCIENCE is situated in the Lowther Arcade, near Charing Cross, in the Strand, which is kept for the exhibition of models of all kinds of machinery; there is to be seen the Steam-Gun of Perkins, which showers forth bullets, more than one hundred and sixty every minute, and we could not help thinking, if universally adopted, the Steam-Gun would go far towards putting an end to war. For when the inventions of man have so far improved the numerous instruments of destruction; so that men marching to a breach in a fortress, go to certain death, no word of command will urge them forward. And the strong man will then no longer be able to tyrannize over the weak. For provided any fortress is but provided with a few steamguns, throwing out bullets made of iron instead of lead, column after column would be mown down. Ships, which at present attack forts, almost with a certainty of success, would by a well pointed steam-gun, have their decks swept of their men and they themselves would be perforated through and through and be sunk. We can also conceive there would be no difficulty if the balls were of iron in firing them red hot. And then the trifling expence of the machine required for the steam-gun, places it within reach of every body's pocket. We saw here very beautiful models of locomotives, and of engines, and machines of all descriptions. And we also saw the Daguerreotype which is the most extraordinary production of modern times. We know not how better to describe it than to say, that it is embodying a shadow, or, in other words, that it permanently fixes upon a plate previously prepared for the purpose, the reflection of houses, trees, &c., and the picture is more perfect than any painter can make it. The French government purchased the discovery of Monsieur Daguerre, and very kindly made it known to the public. In a room fitted up as a Theatre, with shutters by which the light can be totally excluded, M. Dele Croix, a French gentleman, explains all the process. Five distinct processes are required to perfect a drawing by means of the Daguerreotype. The plate which is of thin copper silvered over, must be carefully polished, an operation requiring much care and nicety of hand, very fine pumice stone is applied in the first instance with cotton and oil. It is then applied with dried cotton, after which, a small quantity of

diluted nitric acid is carefully dropped on the plate, and accurately distributed over the surface, another light polishing succeeds, after which, the plate is heated over a spirit lamp, which must be moved beneath by the hand so as to distribute the heat equally; or, which is preferable over charcoal, until its surface is evenly covered with a white appearance like a veil spread over it, when it must be suddenly cooled by laying it on a cold stone or a marble table; after this process, the operation of the acid is repeated three times, but the plates are generally put by after it has been twice applied, that the operation may not be too long delayed; the third and last application must be made immediately before the plate is used. This polishing is the only part of the operation that can be said to be seen : for in all the others, except placing the plate in the Camera, which in the Adelaide Gallery was done out of the room, the day light must be excluded, and the light of a small taper is alone allowable. As soon as the plate is polished, the shutters are closed and the operator places the plate in a close box to undergo the second process— The application of a sensitive coating. This is done by fixing the plate face downwards in a box contrived for the purpose, in the bottom of which stands a cup with Iodine, broken into small pieces and covered with gauze. The fumes of the Iodine rise, and being evenly distributed by the gauze, spread themselves over the plate, which, within half an hour is covered with a fine coating of a yellow gold colour. The moment it has acquired a sufficient coating of the lodine, it is removed to a box, and being closed up, the third process is, preparing the Camera Obscura and placing the plate in it. In order to judge of the effect of the object to be represented, the focus is regulated through a powerful lens, on a plate of ground glass occupying the position in which the prepared plate is to be placed. When every thing is properly adjusted, the box containing the plate is introduced and exposed to the focus of the Camera. The time necessary to complete an impression varies according to the power of the sun's rays, sometimes in about twenty-five minutes a representation is formed on the plate, or speaking otherwise, the shadow is then embodied.

The fourth operation is bringing out the image. To do this, the board with the plate is removed from the box and adjusted face downwards, at an angle of forty-five, in an iron box contrived for the purpose, in the bottom of which is a cup of mercury which is heated by a spirit lamp placed beneath ; after it has remained here some time, it is replaced in the case with folding doors until the fifth and last process (removing the sensitive coating) is performed. This operation is to remove a portion of the Iodine when a solution of common salt is made use of. The plate is first dipped in common

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