AN EVENING AT THE POLYTECHNIC INSTITUTION.
Br a recent arrangement, and a very good one it was, this Gallery of Art and Science is opened every evening from seven till ten ; when, in addition to the multiffirious objects of curiosity, a popular lecture is given on some point of chemical science, which is illustrated by ex- periments. We passed an hour or two there the other evening, very pleasantly ; and we will indicate the leading features of the exhibition, for the benefit of young holyday-makers, to whom this offers instructive and entertaining recreation : a large proportion of the company, indeed, were of this sort, and very much interested they appeared. On entering the hall, you see on one hand a person spinning glass in threads finer than a spider's web mid as pliant as silk, for the purpose of weaving into a thbric for apparel, his only implements being a gas blow-pipe to fuse the stick of glass and a spinning-wheel to wind off the vitreous film : on the other hand an ingenious Italian, with an appa- ratus like a portable batterie dc cuisine, is casting miniature busts and small models of various objects iu wax of different colours, which he hardens so as to resist a blow and even a considerable degree of beat. There are other things to attract attention; but as the scientific perform- ances in-the gallery commence at half-past seven, we will proceed up stairs,—only stopping a moment to see the profilist cutting out with scissors, in black paper, a silhouette of some good-looking gentleman, who stands with his eye resolutely fixed upon the wall in the manner of one cutting an acquaintance : the likeness is recognizable, though it has been taken by eye only, not from a diminished shadow; and the operation taxes neither the patience nor the pocket, for the time it takes is but a minute, and the charge is oily sixpence. But the bell rings, and the rush to the other end of the gallery announces that the diving operations are commencing. The diver in his shapeless dress and helmet-head—a chrysalis of humanity—descends into the well, and holding the packthread cable of a tiny model of a ship's hull, like Gulliver towing the Blefuscudian fleet, disappears ; when presently a pair of hands emerges, and it is dragged down, in a sort of mimic mael- stsoons, as if .Neptusw 'pulled under water the Royal George, of which ill-fatedy ship:611s, toy is the representative. The conducting- 'Area of a galvanic ;battery having been attached to the vessel, the diVer comes up, and the other end of the wires being put in con- nexion 'with' the 'battery,' a deadened sound of explosion is heard, a 'slight shock is felt; and a column of foam rises to the surface, scattering the Wreck of Royal George the little; thus exemplifying on adman! scale the effect of Colonel Fanny's proceedings for blowing up the wreck of.the great Royal George. The diver, then taking the two poles ofa galvanic wire with a bit of charcoal attached to each, descends Apia, and by merely putting them into contact, the charcoal is ignited -under water, and the flame is distinctly visible at the depth of several feet; though none of the charcoal is consumed, for the voltaic light exists independent of combustion, which water would prevent of course. Other Odious effects of electric or voltaic light are also exhibited: it is made to pass through three eggs, without cooking them or injuring them in the least, though they appear for a moment all aflame within : oranges also are made to look like red-hot balls by the same agency. The in- conceivable velocity of the electric fluid is illustrated by the voltaic telegraph, the wire of which runs the whole circuit of the gallery— several hundred feet: the test is in the simultaneous explosion of small charges of gunpowder at each corner of the room by the galvanic contact in the centre. Other attractive displays of electrical phenomena of more ordinary kinds are made in Mr. Baciinossana's lecture on electro-magnetism ; and the lecture of Mr. COOPER, on light and combustion, delivered in the theatre on alternate evenings, in lieu of the hydro-oxygen microscope, is a brilliant display of chemical pyrotechnics, independently of the scientific information it conveys. Mr. COOPER, in the course of his lecture, gives a striking instance of the effect of various lights on colours, and of different substances on flame, in the combustion of metals and the ,inflammation of gases. On these occasions, too, the Daguerrilotype pic- tures are exhibited under the Rude light, which brings out their effects of light and shade very powerfully : they appear at first sight like exquisitely-finished engravings on steel plate; but on close inspection their extreme delicacy and minuteness, requiring a lens to perceive all the details, makes it evident that no human hand, however skilful, could produce such infinitely fine lines ; and on looking along the surface of the plate, the absence of any incision, or indeed of all trace of delinea- tion, has a magical effect. The precise accuracy with which the form and substance of every individual object is depicted, with unerring cor- rectness of perspective and light and shadow, combining breadth of effect with the microscopic exactness of parts, makes the Daguerreotype plates invaluable as documentary representations ; but they require to be translated into a style of art and on a scale better suited to human eyes. The microscope, -which is exhibited in the commodious theatre of the Institution, is perhaps more popular than Mr. COOPER'S lecture on light ; the absence of which is compensated by that of Mr. BACH- , HOMER on electricity : the style of both lecturers, we may remark, is very agreeable, their delivery distinct, and the explanations lucid. This theatre would be a capital place for a short lecture on astronomy : from a portion of an orrery suspended in the gallery we infer that some such illustration of our solar system is either given or intended to be. The diving-bell is in constant requisition, and the visiters flock to see those who have been dawn in it come out, as if they would be certain their clothes were not wetted, or that they were alive after being under water a few minutes ; and almost all who come out of the bell put their fingers to their ears, as if to remove the imaginary plug which the pressure of the air thrusts into them. Really it is a great con- 'venience to descend in a diving-bell and see miniature Royal Georges blown up, and sub-marine patrols walking about under water with a light to guide their steps, by only going to Regent Street and paying a shilling. The ocean is represented by a portable canal with a tank in the middle; which canal, moreover, floats a little fleet of model-craft of various nations-; and exhibits the action of locks and water-wheels, the launch of a ship, &se.
A pair of enormous reflectors at opposite extremities of the gallery afford a good deal of amusement by making a whisper at one end au- dible at the other ; and on one occasion the transmission of heat as well as sound was demonstrated by cooking a cutlet at the reflection in one disc of a fire in a grate placed before the other twenty yards off. To enumerate the various curiosities would be tedious, if practicable ; but the pneumatic telegraph, which is shown in action ; and Mr. Ssow liana's's lightning-conductors for ships, whose efficacy is prac- tically exemplified by a mimic thunder-cloud transmitting the electric fluid, ought not to be passed unnoticed. The models of new inventions and specimens of manufacture are numerous, and many of them curious and beautiful. The works of art are not of the finest kind; a collection of small Indian figures being the only specimens worth notice. To give at idea of the miscellaneous character of the objects that line the gallery, we may mention, that in the same case with some
figured satins, are the robe of a New Zealander and the horn armour of another savage ; the grass hammock of a Peruvian competes with Dr. A liNOTT'S floating bed and the flexible fauteuil : a colossal anato- mical model of' the human ear is placed close to the harp and adoplion ; and safety stone coffins and fowling-pieces are in juxtaposition. Every article is labelled, but the peculiar merits of most require a more specific explanation. Tine uses of an institution of this nature are manifold and obvious. We would suggest that popular lectures on other branches of natural science besides chemistry might be given with advantage I not that there is any lack of variety in the attractions, which are abundant in- deed, the shilling admission considered; but we mean as an extra thing,, independent of the current exhibition.
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