occupy, for situations where room cannot be spared to much

extent.

One which is capable of furnishing gas for from 12 to 20 argand lights, may be conveniently placed in such a fire-place as is usually found in back kitchens, and will occupy a space only of about 3 feet square, or more conveniently of 4 feet by 3, and will require a height of about 8 feet.

The large apparatus shewn in the plate measures in front 10 feet, and in depth 6 feet, and is also about 8 feet high.

The intermediate sizes are made up by adopting either one stove of the large or smaller sizes to its proper feeding and washing apparatus; or by fixing two stoves, of such dimensions as may be required to a common feeding apparatus, as shewn in the plate.

The latter plan is the best, as it is a security against any disappointment, for as the stoves may thus be worked either singly or together, it gives the power of cleaning or putting the one in order, without any hinderance to the process.

The space mentioned as occupied by this gas apparatus is, of course, independent of that necessary for the gazometer, or reservoir of gas, which is variable according to the consumption required.

For private houses, a gazometer should hardly contain less than from 80 to 100 cube feet, and for mansions and larger establishments they should hold from 300 to 600 cube feet. There are great advantages in having the gazometer as large as circumstances will admit; in the first place, the demand of the longest night in winter should be provided for, and the increased consumption occasioned by lighting the greatest number of rooms for company. In the second place, both the trouble and expense of the gas is diminished by having a reservoir sufficiently capacious to hold some days' ordinary consumption, by which, as the gas improves by keeping, it is most convenient and economical to have to make it but occasionally, as, for instance, once or twice in the week.

In a moderate private house, where three or four rooms are adequately lighted, and where a small flame is kept burning all

night in a bed-chamber, it has been found that from 20 to 30 cube feet of oil-gas is sufficient; and, therefore, a gazometer containing 100 feet will give a supply for four nights.

Such a gazometer will be about 6 feet long and 4 wide, and rather more than 4 feet high. One for 400 cube feet may be 10 feet long, and 7 wide, and about 6 high, and larger ones, of course, in proportion.

There is no occasion that a gazometer should be placed near the other parts of the apparatus, though they are, for the convenience of description, so exhibited in the plate; and, indeed, at Apothecaries' Hall, from which the drawing has been made, the gazometer is not so placed, but is at a distance in the yard, where it was originally fixed and used for coal-gas. No inconvenience arises from the gazometer being apart from the rest, and it allows of placing them out of the main building, either in any yard or out-building that may be at hand.

Description of the Oil-gas Apparatus.

AA (Plate I.) Figure 1, Stoves made of cast iron, and lined with brick-work, containing the retorts.

a Doors to get at the retort mouths for cleansing them.

b Fire door. c Ash-pit.

B Iron-stand, or frame, supporting the condenser, oil-cistern, and wash vessel.

C Oil-cistern. D Cock, to permit the oil to enter the cistern by the funnel E, or, by turning it in another direction, to flow into the retorts by the pipe F.

dd Small index cocks, to govern the admission of the oil

in the retorts.

These parts are shown upon a larger scale in Fig. 2. GG Perforated columns, by which the oil descends to the retorts. HH Perforated columns, by which the gas ascends from the re

torts, and is carried by the moveable pipe I, to the conden ser in the case J. This case is filled with cold water, surrounding the condenser.

The columns are fitted with stoppers on their tops, which are easily taken out for the convenience of cleaning.

K A short pipe, communicating from the bottom of the condenser to the top of the oil-cistern; this conveys the condensed oil at once into the latter, and suffers the surface of the fluid in it to be acted upon by the same pressure as exists at all times in the retorts.

LA pipe to convey the gas from the condenser to the washvessel M.

e Screw plug, to allow water to be poured into the wash vessel.

f A cock to draw water from the wash vessel.

A cock to regulate the height of water in the wash vessel, and to draw off condensed oil, as it may occasionally accumulate there.

N Pipe to convey the gas from the wash vessel to the gazometer. O Plate II., Pipe rendered flexible by knuckle-joints, to convey the gas into the gazometer at the top.

P A similar pipe, leading the gas to the tubes, which conduct it to the burners.

Q Gazometer made of sheet-iron, and suspended by a chain. over pulleys, with a counterpoise. It is placed in water in the usual manner, which may be contained in a brick tank, or in a cistern of wood or cast-iron, as circumstances may render most convenient.

ART. XI. Some Account of the Character and Merits of the late Professor PLAYFAIR.

[We regret that it has not been in our power to obtain materials for a more extended account of the two eminent persons, whose Biography is sketched in this and the succeeding article, and are not without hopes of accomplishing this on a future occasion. In the mean time, we have thought well to insert the following notices, which originally appeared in the Times newspaper, and which are from the pen of a very spirited writer.]

IT has struck many people, we believe, as very extraordinary, that so eminent a person as Mr. Playfair should have been allowed to sink into his grave in the midst of us, without

calling forth almost so much as an attempt to commemorate his merit, even in a common newspaper; and that the death of a man so eminent and so beloved, and, at the same time, so closely connected with many who could well appreciate and suitably describe his excellencies, should be left to the brief and ordinary notice of the daily obituary. No event of the kind certainly ever excited more general sympathy; and no individual, we are persuaded, will be longer or more affectionately remembered by all the classes of his fellow-citizens; and yet it is to these very circumstances that we must look for an explanation of the apparent neglect by which his memory has been followed. His humbler admirers have been deterred from expressing their sentiments by a natural feeling of unwillingness to encroach on the privilege of those, whom a nearer approach to his person and talents rendered more worthy to speak of them; while the learned and eloquent among his friends have trusted to each other for the performance of a task which they could not but feel to be painful in itself, and not a little difficult to perform as it ought to be; or, perhaps, have reserved for some more solemn occasion that tribute for which the public impatience is already at its height.

We beg leave to assure our readers, that it is merely from anxiety to do something to gratify this natural impatience, that we presume to enter at all upon a subject to which we are perfectly aware that we are incapable of doing justice; for of Mr. Playfair's scientific attainments, of his proficiency in those studies to which he was peculiarly devoted, we are but slenderly qualified to judge: but, we believe, we hazard nothing in saying that he was one of the most learned mathematicians of his age, and among the first, if not the very first, who introduced the beautiful discoveries of the latter continental geometers to the knowledge of his countrymen, and gave their just value and true place in the scheme of European knowledge to those important improvements by which the whole aspect of the abstract sciences has been renovated since the days of our illustrious Newton. If he did not signalize himself by any brilliant or original invention, he must at least, be allowed to have

been a most generous and intelligent judge of the achievements of others, as well as the most eloquent expounder of that great and magnificent system of knowledge which has been gradually evolved by the successive labours of so many gifted individuals. He possessed, indeed, in the highest degree, all the characteristics both of a fine and powerful understanding, at once penetrating and vigilant, but more distinguished, perhaps, for the caution and sureness of its march, than for the brilliancy or rapidity of its movements, and guided and adorned through all its progress by the most genuine enthusiasm for all that is grand, and the justest taste for all that is beautiful in the truth or the intellectual energy with which he was habitually

conversant.

To what account these rare qualities might have been turned, and what more brilliant or lasting fruits they might have produced, if his whole life had been dedicated to the solitary cultivation of science, it is not for us to conjecture; but it cannot be doubted that they added incalculably to his eminence and utility as a teacher; both by enabling him to direct his pupils to the most simple and luminous methods of inquiry, and to imbue their minds, from the very commencement of the study, with that fine relish for the truths it disclosed, and that high sense of the majesty with which they were invested, that predominated in his own bosom. While he left nothing unexplained or unreduced to its proper place in the system, he took care that they should never be perplexed by petty difficulties, or bewildered in useless details, and formed them betimes to that clear, masculine, and direct method of investigation, by which, with the least labour, the greatest advances might be accomplished.

Mr. Playfair, however, was not merely a teacher; and has fortunately left behind him a variety of works, from which other generations may be enabled to judge of some of those qualifications which so powerfully recommended and endeared him to his contemporaries. It is, perhaps, to be regretted, that so much of his time, and so large a proportion of his publications, should have been devoted to the subjects of the Indian astronomy, and