The Bude light originally consisted of an oil argand flame, having a stream of oxygen thrown up over its internal surface, which produced a very vivid illumination. It was found, however, after having been used some time in lighting the House of Commons, that oil lamps thus fed with vital air were expensive, and difficult to regulate. Mr. Gurney then tried to illuminate the House with a raphthalized coal-gas, in argand burners, similarly supplied with oxygen; and though this produced a light of sufficient intensity, he encountered a formidable obstacle to its continuance from the deposition of liquid naphtha in the tubes of distribution. He next happily discovered a method of obtaining, from ordinary coal-gas, purified in a simple apparatus of his own, and burned with oxygen derived from the atmosphere, an effulgence adequate to every purpose of internal and external illumination, which is now used in the House of Commons with perfect success, and at a cost of only twelve shillings per night, whereas that of the candles previously used there amounted to six pounds eleven shillings per night.

This new Bude light possesses the following advantages over all other kinds of artificial illumination hitherto displayed.

First.-It gives as much light as the best argand gas flames, with only one half the expenditure of gas. This very remarkable fact was established by experiments carefully performed with the same standard wax candles which I employed for comparison prior to my examination before the late committee appointed to ascertain the best mode of lighting the House of Commons. A common argand gas flame was found to emit light equal to ten such candles (three to the pound), and a Bude burner, called No. 10, gave a light equal to 94.7 of the candles. Thus the Bude flame had nearly ten times the illuminating power of the gas argand flame; while, by means of an accurate gas-meter, the former was ascertained to consume only 4.4 times the quantity of gas consumed by the latter, demonstrating the economy of the Bude light over common gas to be greater than two thirds; and this economy increases in proportion to the magnitude of the light. The source of this surprising superiority may be observed by comparing the two flames: the base of the argand gas flame is of a blue tint for fourteen-sixteenths of an inch, a space in which the gas burns with intense heat, but little or no light; whereas the base of the Bude flame acquires a dazzling whiteness at three-sixteenths of an inch from the metal. Thus we see, that, through a range of eleven-sixteenths of an inch, the common gas argand flame is wasted in producing the nuisance of heat without light. Secondly.-From the phenomena just noticed, as also from the circumstance of the Bude flame emitting a double light with a single volume of gas, when compared with the gas argand, it is manifest that the former, in equal degree, can disengage at the utmost only half the heat that the latter does.

Thirdly.-The Bude light simplifies greatly the means of artificial illumination, since it concentrates in one flame as much light as will diffuse, throughout a large apartment, a mid-day lustre, which may be softened by shades of every hue, and reflected by mirrors in every direction.

F

Fourthly. From this property proceeds its value as a ventilator, since the single tube which carries off the burned gases serves to draw out also the effluvia from a crowded chamber.

From all these facts, I am of opinion that Mr. Gurney's new Bude light is a most meritorious invention, for both public and private buildings, as it removes altogether the objections hitherto justly urged against the use of the highly hydrogenous gas of the London companies in dwelling-houses, namely, that its heat is great in proportion to its light, when compared with the more highly carburetted gases of Edinburgh and Glasgow. The time must therefore be now at hand when the great economy and convenience of lighting private houses with gas will be experienced by the inhabitants of the metropolis, as they have been for such a considerable time by those of every town of importance in Scotland. That the same quantity of coal-gas may be made to produce a double amount of illumination in Mr. Gurney's patent burner to that obtained from it in an ordinary argand, will appear to many a paradoxical, if not a doubtful, proposition. Of its reality, however, I am fully convinced, and I think the fact may be accounted for in the following way :

Light, in general, is proportional to the intensity of ignition, a truth well exemplified in the effect of the oxy-hydrogen flame upon a bit of lime or clay. On the same principle, when the flames of two candles are brought into close contact, they afford a compound light considerably greater than the sum of their separate lights. Now, Mr. Gurney's burner gives such a compound flame. It consists of two or more concentric cylinders of flame, mutually enhancing each other's temperature, just as in Fresnel's polycycle oil argand lamps used in the French lighthouses.

In addition to the augmented intensity of ignition, we must also take into account the peculiar nature of the combustion of carburetted hydrogen gas, whether as generated from coal in a retort, or from oil in a lamp. The vivid whiteness of its flame is due to the separation in solid particles, and subsequent ignition of its carbon. Pure hydrogen, when burned, affords a very feeble light; and whenever so much air is mixed with coal gas, as is sufficient to consume all its carbon simultaneously with its hydrogen, it burns with a dim blue flame. Now, in the base of a common argand flame, an excess of cold atmospheric oxygen is allowed to act upon the coal gas in the vacant spaces between the pin-holes, whereby the temperature being greatly lowered, while the carbon is consumed in the gaseous state, the light from these two causes is nearly null. It is not till the gaseous mixture rises and forms a continuous hot cylinder, without interstitial streams of air, that it emits a white light from the ignited particles of the carbon preçipitated in the interior of the flame.

In Mr. Gurney's concentric series, the prejudicial excess of atmospheric air is prevented, and only so much permitted to come into contact with the gas, as will effect the due separation and ignition of its carbon, even at the origin of the flame. To these two causes conjoined, viz. the increased intensity of ignition, and the limited supply

of oxygen, it is that the new Bude flame owes its economy of illumination. The effect of oxygen in excess is elegantly demonstrated by throwing up a stream of it within a gas argand flame, for the light is thus nearly annihilated, while the heat is prodigiously augmented. As regards the specification of the patent for this improved mode of lighting, which I have carefully examined, I have no hesitation in declaring it, in my opinion, to be valid and unimpeachable.-The London Journal and Repertory of Arts, Sciences, and Manufactures.

NEW GAS-BURNERS.

MR. H. DIRCKS has read to the British Association a paper on the construction of Luntley's Shadowless Gas-burners, and the shape of Glass Chimneys for Lamps. The object of the burner is to bring the gas issuing from the small orifices into direct contact with atmospheric air at the ordinary temperature. Mr. Dircks contends that the heating of the air previously to its combustion diminishes the brightness of the flame; because, while each volume of carburetted hydrogen gas requires ten volumes of atmospheric air for its perfect combustion, the expansion of the air by heat necessarily reduces the weight of oxygen contained in the same volume of air; and, therefore, unless some means be adopted of increasing the supply of air, the oxygen will be deficient. Another alleged advantage of the burner arises from the small quantity of metal through which the orifices are perforated, for by that means a smaller quantity of heat is abstracted in burning. The peculiarity in the form of the glass chimney consists in having the upper end enlarged. The effect of this enlargement, Mr. Dircks states, is to open the top of the flame, and increase its brightness.

IMPROVED CHAMBER-LIGHT.

THE rush being apt to fail, and the oil light, unless skilfully managed, occasioning obvious inconvenience, the following contrivance may be considered an improvement on the old fat light with a paper wick :-Provide a common cylindrical ointment pot, a two-ounce size in the winter; in the summer, a smaller one. This is filled with any kind of fat, as with the waste fat from the kitchen. This is trimmed by about half an inch of the common wax wick sold at the tallowchandler's, being simply stuck into a thin slice of wine-bottle cork, upon which first place a strip of stout filtering paper; this is about half the diameter of the cork in breadth, and a diameter and a half in length. It need not be quite so broad, but it must be at least the length stated. The reason for using the bibulous paper is that it feeds the wick properly; without it, or some such contrivance, it will not burn.

Remove with the handle of a tea-spoon sufficient of the fat to allow the cork to be a little below the surface, and then place the fat so removed over the cork and paper, neatly spreading it, to make an even surface. The light is now prepared. Probably the plan might

be improved, for the convenience of those who are not early risers, by having an aperture at the bottom of the pit, and placing it in water, which would rise to the level when the fat is melted, and extinguish the wick when it is exhausted. If not extinguished when the fat is burned up, the cork, &c. will be consumed, and occasion an unpleasant smell.

LIGHTING AND VENTILATING.

On April 7th, Professor Faraday read, at the Royal Institution, a paper on Lighting and Ventilating. The subject was interesting, not from any novel theory, but for the application of known facts to useful purposes, especially Lighting and Ventilating,-ventilation being here used in its common acceptation, as meaning only the mode of withdrawing, from places where human beings are to live, the bad air consequent on combustion, and so leaving the atmosphere in its natural condition, in which alone it can be beneficial to man. After some general remarks on the nature of combustion, the consequent formation of water and carbonic acid, Mr. Faraday described the new process for which his brother has taken out a patent, and exhibited a chandelier to which it had been applied. The ordinary glass chimney is first placed on the lamp, which is fed with external air, as usual: a second chimney, somewhat larger and taller, is then put on, and covered with a thin sheet of mica. In the space between the glasses there is no communication with the external air, except through what Mr. Faraday called an aërial sewer, which sewer is intended to carry off the heated and decomposed air, and is continued till the air is discharged outside the house, or into the flue of a chimney. In brief, the invention consists in the application of the down-drawing stove principle to a lamp burner. This arrangement, in the chandelier exhibited, formed a part of the central support, and was ornamental as well as useful.

Trial was made between the celebrated inventions-the Bude and Faraday Lights, fixed for that purpose in two of the libraries of the Reform Club. The result of the experiment was in favour of the Bude Light as to the brilliancy of illumination, the perfect ventilation, and the freedom from heat. The Bude gives a light equal to 30 argands, and lights the room perfectly at every point. The Faraday light consists of 18 lights, and the smoke of the gas is carried off by tubes. The heat increased six degrees after the Faraday was lighted; it is of a subdued tone, and far from brilliant. It will thus be seen that the Bude has added to its fame by these experiments, the more by reason of both lights being great improvements upon the old system. The Bude, we believe, has been quietly but rapidly gaining in public estimation, and to the many public and private edifices which now possess it, the principal clubs will, doubtless, soon be added. During the experiments it was stated that the Faraday light was about four times more expensive than the Bude.-Times, Nov. 8th.

VENTILATION OF LIGHTHOUSE LAMPS.

PROFESSOR FARADAY has read to the Institution of Civil Engineers, a paper "On the Ventilation of Lighthouse Lamps; the points necessary to be observed, and the manner in which these have been or may be attained."

The author states that the fuel used in lighthouses for the production of light is almost universally oil, burnt in lamps of the Argand or Fresnel construction; and, from the nature and use of the buildings, it very often happens that a large quantity of oil is burnt in a short time, in a small chamber exposed to low temperature from without, the principal walls of the chamber being only the glass through which the light shines; and that these chambers being in very exposed situations, it is essential that the air within should not be subject to winds or partial draughts, which might interfere with the steady burning of the lamps.

If the chamber or lantern be not pefectly ventilated, the substances produced by combustion are diffused through the air, so that in winter, or damp weather, the water condenses on the cold glass windows, which, if the light be a fixed one, greatly impairs the brilliancy and efficiency, or, if the light be a revolving one, tends to confound the bright and dark periods together. The extent to which this may go may be conceived, when it is considered that some lighthouses burn as much as twenty, or more, pints of oil in one winter's night, in a space of 12 or 14 feet diameter, and from 8 to 10 feet high, and that each pint of oil produces more than a pint of water; or from this fact, that the ice on the glass within, derived from this source, has been found in some instances an eighth, and even a sixth, of an inch in thickness, and required to be scraped off with knives.

The carbonic acid makes the air unwholesome, but is easily removed by an arrangement which carries off the water as vapour. One pound of oil in combustion produces 1.06 pounds of water and 2.86 pounds of carbonic acid.

The author's plan is to ventilate the lamps themselves by fit flues, and then the air inside the lantern will always be as pure as the external air; yet having closed doors and windows, a calm lantern, and a bright glass.

EFFECTS OF INTENSE HEAT.

AFTER the great conflagration at Hamburgh there were abundant opportunities for examining the effects of high degrees of Heat. There were bricks the surface of which were fused, and thus coated with enamel; lime had become brittle and loose, and re-acquired its caustic property; pieces of granite burnt into fragments, and the surface of many square stones separated into thin layers. The beils were partly fused, at the same time becoming oxidated, and forming a slag and red-copper ore. A portion of the fused metal broke through the vaults and entered the sepulchres, coating and filling the skulls and bones with metal;-and the bell-metal underwent a partial refining, the tin being separated by fusing, and the copper left behind in