tity of remarkably choice and scarce wine. The gentlemen of his suite, whose taste was hardly second to their master's, finding it had not been demanded, thought it was forgotten, and, relishing its virtues, exhausted it almost to the last bottle, when they were surprised by the unexpected command that the wine should be forthcoming at an entertainment on the following day. Consternation was visible on their faces; a hope of escaping discovery hardly existed, when one of them, as a last resource, went off in haste to a noted wine-brewer in the city, numbered among his acquaintance, and related his dilemma. 'Have you any of the wine left for a specimen?' said the adept; 'O yes, there are a couple of bottles.' 'Well, then, send me one, and I will forward the necessary quantity in time; only tell me the latest moment it can be received, for it must be drunk immediately.' The wine was sent, the deception answered; the princely hilarity was disturbed by no discovery of the fictitious potation, and the manufacturer was thought a very clever fellow by his friends. What would Sir Richard Steele have said to so neat an imitation, when in his day he complains that sinister fabrications were coarsely managed with sloe-juice? The science of adulteration must then have been in its infancy."

The sources from which the editors appear to have derived most of their "additions," are all of the second and ready-athand sort, such repositories of difficult access as the Penny Magazine and Illustrated News. We have not met with a single instance of original information, or of search after it. Of two passages which we have marked for quotation as the newest in the book, one is extracted from a commu

nication "By a Correspondent," (a volunteer, no doubt,) and the other borrowed from "Illustrated" cotemporary:

our

Golden Glass.

I shall now conclude these observations by a few notices respecting glass tinged by fusion with gold, which, though never brought into general use among glass-painters, has, I know, been employed in one or two instances, flashed both on crown and on flint-glass. Not long after the time when the art of making the copper-red glass was lost, Kunkel appears to have discovered that gold melted with flint glass was capable of imparting to it a beautiful ruby colour. As he derived much profit from the invention, he kept his method secret, and his successors have done the same to the present day.

The art, however, has been practised ever since for the purpose of imitating precious stones, &c., and the glass used to be sold at Birmingham for a high price under the name of Jew's Glass. The rose-coloured scentbottles, &c., now commonly made, are composed of plain glass, flashed or coated with a very thin layer of the glass in question., I have myself made numerous experiments on this subject, and have been completely, and at last uniformly, successful, in producOne ing glass of a fine crimson colour. cause why so many persons have failed in the same attempt,* I suspect is, that they have used too large a proportion of gold; for it is a fact, that an additional quantity of gold, beyond a certain point, far from deepening the colour, actually destroys it altogether. Another cause probably is, that they have not employed a sufficient degree of heat in the fusion. I have found that a degree of heat, which I judged sufficient to melt cast-iron, is not strong enough to injure the colour. It would appear, that in order to receive the colour, it is necessary that the glass should contain a proportion either of lead, or of some other metallic glass. I have found bismuth, zinc, and antimony to answer the purpose, but have in vain attempted to impart any tinge of this colour to crown-glass alone.

Glass containing gold exhibits the same singular change of colour on being exposed to a gentle heat. The former when taken from the crucible is generally of a pale rosecolour, but sometimes colourless as water, and does not assume its ruby colour till it has been exposed to a low red-heat, either under a muffle or in the lamp. Great care must be taken in this operation, for a slight excess of fire destroys the colour, leaving the glass of a dingy brown, but with a blue transparency like that of gold-leaf. These changes of colour have been vaguely attributed to change of oxygenation in the gold; but it is obviously impossible that mere exposure to a gentle heat can effect any chemical change in the interior of a solid mass of glass, which has already undergone a heat far more intense. In fact, I have found that metallic gold gives the red colour as well as the oxide, and it appears scarcely to admit of a doubt, that in a metal so easily reduced, the whole of the oxygen must be expelled long before the glass has reached its melting point. It has long been known that silver yields its colour to glass while in the metallic state, and everything leads one

Dr. Lewis states that he once produced a potfull of glass of beautiful colour, yet was never able to succeed a second time, though he took infinite pains, and tried a multitude of experiments with that view.-Commerce of Arts, p. 177.

use.

The Wenham Lake Ice.

Ice is now used extensively for a variety of economical purposes, such as packing salmon, cooling liquors, &c. Of late years it has become a regular article of commerce. In September 1833, a cargo of ice, shipped at Boston, was discharged at Calcutta. It was sold at threepence per pound, while the native ice fetched sixpence. It was packed in solid masses, within chambers of double planking, with a layer of refuse tan or bark between them. The quantity shipped was 180 tons, of which about 60 wasted on the voyage, and 20 on the passage up the river to Calcutta. Thousands of tons are now annually shipped from Boston (United States) to our East Indies, to the West Indian Archipelago, and to the Continent of South America, and quite recently "The Wenham Lake Ice Company" have erected extensive ice houses in London and at Liverpool, and arranged for the transportation to this country of thousands of tons of ice. One surprising circumstance connected with the trade, is the fact that their ice, though transported to this country in the heat of summer, is scarcely reduced in bulk. The masses are so large, that they expose a very small surface to atmospheric action in proportion to their weight, and therefore do not suffer from exposure to it, as the smaller and thinner fragments do, which are obtained in our own or other warmer climates. It appears, also, that ice frozen upon very deep water, is more hard and solid than ice of the same thickness obtained from shallow water; and even when an equal surface is exposed, melts more slowly. In this country, the collection of ice, even by those largely engaged in the trade, is an occasional and fitful undertaking; depending, both as to time and quantity, upon the accidental occurrence of severe frost; and when the process of collection is carried on, it is with very few artificial aids. In America, on the other hand, this labour can be regularly carried on through the whole winter; while the adjuncts of machinery for cutting and storing, and of steam for transporting it, are brought extensively into action.

The details connected with this trade, as carried on in America, are so novel and so

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interesting, that we lay them before our readers with the confident belief that the result of our labours will prove attractive to them. Wenham Lake, whence a large proportion of the ice now imported to this country is obtained, is eighteen miles from Boston, in the State of Massachusetts; it occupies a very elevated position, and lies embosomed in hills of majestic height and bold rugged character. The lake has no inlet whatever, but is fed solely by the springs which issue from the rocks at its bottom, a depth of 200 feet from its surface. The ice-house, which is capable of storing 20,000 tons of ice, is built of wood, with double walls, two feet apart, all round; the space between which is filled with sawdust; thus interposing a medium, that is a nonconductor of heat, between the ice and the external air; the consequence of which is, that the ice is scarcely affected by any condition or temperature of the external atmosphere, and can be preserved without waste for an indefinite time.

This

The

The machinery employed for cutting the ice is very curious, and was invented for that express purpose. It is worked by men and horses in the following manner :-From the time when the ice first forms, it is carefully kept free from snow until it is thick enough to be cut: that process commences when the ice is a foot thick. A surface of some two acres is then selected, which at that thickness will furnish about 2000 tons, and a straight line is then drawn through its centre from side to side each way. A small hand-plough is pushed along one of these lines, until the groove is about three inches deep and a quarter of an inch in width, when the "marker" is introduced. implement is drawn by two horses, and makes two new grooves, parallel with the first, twenty-one inches apart; the gauge remaining in the original groove. marker is then shifted to the outside groove, and makes two more. Having drawn these lines over the whole surface in one direction, the same process is repeated in a transverse direction, marking all the ice out into squares of twenty-one inches. In the meantime, the "plough," drawn by a single horse, is following in these grooves, cutting the ice to a depth of six inches. One entire range of blocks is then sawn out, and the remainder are split off towards the opening thus made with an iron bar. This bar is shaped like a spade and of a wedgelike form. When it is dropped into the groove, the block splits off; a very slight blow being sufficient to produce that effect, especially in very cold weather. The labour of "splitting" is slight or otherwise, according to the temperature of the atmo

sphere. "Platforms," or low tables of frame-work, are placed near the opening made in the ice, with iron slides extending into the water, and a man stands on each side of this slide, armed with an ice-hook. With this hook the ice is caught, and by a sudden jerk thrown up the "slide" on to the "platform." In a cold day everything is speedily covered with ice by the freezing of the water on the platforms, slides, &c., and the enormous blocks of ice, weighing some of them more than two cwt., are hurled along these slippery surfaces, as if they were without weight. Besides this platform stands a "sled " of the same height, capable of containing about three tons; which, when loaded, is drawn upon the ice to the front of the store-house, where a large stationary platform of exactly the same height is ready to receive its load; which, as soon as discharged, is hoisted block by block into the house.

Forty men and twelve horses will cut and stow away 400 tons a day. In favourable weather 100 men are sometimes employed at once. When a thaw or a fall of rain occurs, it entirely unfits the ice for market, by rendering it opaque and porous; and occasionally snow is immediately followed by rain, and that again by frost, forming snowice, which is valueless, and must be removed by the "plane." The operation of "planing" is somewhat similar to that of "cutting." A plane gauged to run in the grooves made by the "marker," and which shaves the ice to the depth of three inches, is drawn by a horse, until the whole surface of the ice is planed. The chips thus produced are then scraped off; and if the clear ice is not reached, the process is repeated. If this makes the ice too thin for cutting, it is left in statu quo, and a few nights of Ihard frost will add below as much as has been taken off above. In addition to filling their ice-houses at the lake and in the large towns, the company fill a large number of private ice-houses during the winter, all the ice for these purposes being transported by railway. It will easily be believed that the expense of providing tools, building houses, furnishing labour, and constructing and keeping up the railway, is very great; but the traffic is so extensive, and the management of the trade so good, that the ice can be furnished, even in England, at a very trifling cost* (it is retailed at twopence per pound.)

Although, for the reasons we have given, the editing of this work cannot be said to

* For the above account of the mode of collecting the ice at Wenham Lake, we are indebted to the Illustrated London News for May 17, 1845.

redound much to the credit of the brace of doctors who have undertaken the task, it does great credit, nevertheless, to Mr. Bohn and his "Standard Library." As far as bookseller and printer have been concerned, it has been got up in the best possible manner, and must be regarded, on the whole, as being at once the best and cheapest edition of Beckmann now in the market.

SCHONBEIN'S GUN-COTTON.

At the Southampton meeting of the British Association, the following additional particulars were gleaned respecting this extraordinary invention. A patent is in the course of being taken out for it, and this prevented any fuller explanation being given.

The substance is cotton, prepared in a peculiar way. The explosive force is double that of gunpowder; yet the substance leaves no soil on fire-arms. There are two qualities-the second-best causing little smoke, the other none. Gunpowder explodes at 600 degrees of heat; gun-cotton at 400; and it may be exploded on gunpowder without the powder's igniting! Mr. Grove showed experiments with the new explosive. He first exploded a small quantity of gun, powder, for the purpose of showing the large quantity of smoke evolved. He then exploded a small lock of the gun-cotton, of the second quality; it flashed off as rapidly as gunpowder, and but a very small quantity of smoke was perceptible. The paper on which it was exploded was slightly stained. The better kind of the gun-cotton exploded still more rapidly, without any smoke whatever; and it gave out an orangecoloured flame. Mr. Grove next exhibited a peculiar property of the cotton, in not being injured by water. He steeped a piece of the cotton in a glass of water, and then pressed it between blotting-paper to dry; though it could not have been thoroughly dry in the time, the cotton flashed off when the heated wire was applied to it, and without any perceptible smoke. The flash, however, was not in this case so instantaneous as that of the perfectly dry cotton. The last and most curious experiment was the explosion of a piece of the gun-cotton when placed upon loose gunpowder without igniting the latter. The experiment succeeded perfectly, though it requires the cotton to be quite dry to insure its success; for if the combustion be less rapid the gunpowder explodes.

COMPENSATION BALANCES.

Şir,-Allow me to inform your correspondent, W. M. that compensation balances are

applied to chronometers, in order to compensate for the alteration in elasticity which is continually taking place in the pendulum spring, by changes in the temperature of the atmosphere. A spring of any kind will become weaker during increased heat, and the contrary during an accession of cold. In the delicate pendulum spring this change is very sensibly indicated by a decrease or increase in the number of vibrations of the balance. The compensation balance is intended to obviate this irregularity by decreasing the momentum as the temperature rises, and vice versa. If your correspondent wishes a further acquaintance with the principle of action, he will find a tolerable article on the subject in the Penny Cyclopædia, under the head" Compensation Balance." Yours, &c.,

London, Sept. 15, 1846.

W. HISLOP.

MR. DREDGE's bridge ovER THE MOYOLA.

[We quote from the Bath Journal th following description of another bridge on Mr. Dredge's system which he has recently erected over the river Moyola, near Castledawson, county of Derry, the seat of the Right Hon. G. Dawson. It is contained in a letter from Mr. Dredge himself to the Editor.]

"The bridge is a curious structure; it is 86 feet span of a single wing, or bracket, extended over the river, which rests upon masonry on the high ground, and dips to the other side, which is seven feet above the water's summer level. The chains are securely fixed back in the high ground, and the roadway line tied on the other side into the lower level, which compels each side to perform its respective work; the roadway keeping the chains extended, and enabling them in the easiest possible manner, to sustain and convey the weight of the bridge and its load to the top of the pier of masonry, the grand fulcrum of the bridge. And this it is which admits of the great diminution in the chains, namely, from twenty-four links at the base, to two links on the other side of the river, occasioning, as it does, no waste of power, labour, or material, and affording a most clear exemplification of the truth of the principle upon which it is constructed. In further vindication of these assertions, allow me to inform you, that the iron work of the bridge is considerably under five tons weight; and that it was transmitted from Bath to Castledawson, in the north of Ireland, a distance of 400 miles. On its journey it was detained in Dublin two days, and one in Belfast, and the heavy floods obstructed the

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works three days: yet, after all, the bridge was completed in sixteen days from the date the iron work was sent from Bath, the masonry inclusive. In the erection, it occupied but six ordinary days of labour, for sixteen men, who were all strangers to the work. Since my return to this city, the Hon. G. Dawson writes me that the bridge excites great interest in that part of Ireland, that crowds of people flock to see it from all parts of the country, as many as a thousand a day, and all admire and approve of it.' He adds, I hope you have carried away in your mind the dimensions for the best site for a communication on both sides with the island.' This is another bridge over the same river, intended to touch at the end of the island, which has now no approach to it from the main land. The bridge will be 130 feet in length, and the island is about two English acres, beautifully studded with fine timber. I have sent a design for it, &c.; and Captain Robert Peel Dawson writes me, I approve extremely of your plan for the second bridge,' &c.; and adds, I will, in conclusion, take this opportunity of expressing my great satisfaction at the manner in which your contract has been completed.'"

PARKER'S WATER-WHEEL.

[Extract from Report thereon of Committee of the Franklin Institute, June 11, 1846. Secured by patents of October 1829, and June 1840.]

The wheel of Mr. Parker consists of an annular space included between two concentric cylinders, and closed above and below. This space is divided into compartments by means of curved partitions or paddles, against which the water acts to turn the wheel. The wheel is mounted upon an axis, either vertical or horizontal, and the water is introduced into the interior by means of a spiral inclined plane or helix, by which it is delivered at the inner circumference of the wheel, very nearly in the direction of the tangent to its motion. The curve of the buckets is so laid down, that the water issues from the external circumference, with no more velocity than that necessary to clear it from the wheel.

The whole wheel and its helical sluice are introduced into an air-tight box, called by Mr. Parker "a draft," or "draft-box," which is kept perfectly tight by being immersed in the penstock, and into which water can find admission only by passing through the wheel; proper arrangements are made for carrying

off the water as fast as it is delivered by the wheel.

Mr. Parker's wheel is a true wheel of pressure, or "turbine," in which the helical sluice has been substituted for the curved guide placed by M. Fourneyron in the interior of his wheel; it might therefore be expected that, provided the curved paddles of the wheel be properly constructed, the practical coefficient would approach, at least, that given by the ordinary turbine; and the experiments tried by your committee have satisfied them that this is in fact the

case.

Mr. Parker himself, in a letter addressed to the Actuary of the Institute, has explained the advantages which he expected to gain by the introduction of the draft-box, and these are evidently great enough to be secured, even at the sacrifice of some of the power of the machine. "By this arrangement (the introduction of the draft-box into the penstock) we are enabled to place the wheel at any convenient height within the compass of the head and fall, and still have the whole descent of water operate upon it. In some instances of saw-mills of 17 and 18 feet head and fall, the axis of the wheel (which is horizontal) has been placed 8 feet above the surface of the lower level, and the power of the mill appeared in every instance to be the same that it would have been if the wheel had been placed at the bottom of the whole descent. This is often a great convenience, as the wheel may be placed in a situation in which it can be but little impeded by the rise of large streams, and frequently reduces the pitman to a proper length, which otherwise would have to be made so long that it would vibrate or tremble. Another important advantage of this arrangement is, that the wood work necessary for the wheel being submerged, cannot be injured by the changes of the air, and will consequently be very durable; and the wheel is effectually secured from frost in the coldest weather."

While, however, the committee acknowledge the advantages to be thus gained, (and another may be added to them, viz., facility of access at any time to the bottom of the wheel for examination or repair,) they believe that the maximum of useful effect, other things being the same, will always be found by

placing the wheel as nearly as may be on the level of the water in the tail-race, so as to suffer as great a column of the water as possible to act directly by its pressure upon the wheel.

1. In regard to its useful effect, it ranks with the overshot water-wheel and turbine.

2. It possesses the peculiar advantages of the turbine, in reference to the action upon it of back-water or ice, and, like it, can be established either upon high or low falls.

3. It is simple in its construction, and of durable materials, and is for these reasons not expensive, and not liable to get out of order.

4. From its peculiar adjustment, easy access may be had to it at any time for the purpose of inspection or repair.

5. Running at high velocities, no intermediate gearing will be necessary, where such velocities are desirable.

LAW OF PATENTS.-IMPORTED INVEN-
TIONS.

(Vice-Chancellor's Court, Sept. 22, 1846.)

Beard v. Egerton and others.

In this case, which involves the right to patent in England the celebrated Daguerreotype art, an injunction was originally applied for to the Vice-Chancellor of England, when his Honour directed an action to be brought at common law to try the validity of the patent. An action was accordingly brought in the Court of Common Pleas, when the defendants put in various pleas, to which the plaintiff specially demurred. The declaration alleged that the plaintiff became the assignee or purchaser in this country of a patent taken out in the name of Berry, as agent for M. Daguerre, a Frenchman residing in France, for the taking of Daguerreotype pictures. The defendants' pleas were, first, that the plaintiff, as assignee, did not stand in the light of a meritorious inventor; and, secondly, that previous to that assignment, Daguerre had assigned over all his right to the invention to the King of the French, for a certain annuity; and that the King of the French had since made all that information known to the public; and that the defendants had a right to the invention without the leave of the plaintiff: upon which grounds these pleas alleged that the patent was void. To these pleas the demurrer was, that they were not a sufficient answer in law.

Sir T. Wilde, for the plaintiff, submitted that Daguerre himself might have taken out