oil certainly has the advantage. Much depends on the way in which the burners are managed, a proper attention to which will, perhaps, in either case, prevent any unpleasant effects. But on this point we have no satisfactory information.

"Oil gas," say Taylor and Martineau, “burns with a far purer and more brilliant light than coal gas.' With good coal gas we cannot say that we have ever perceived a very material difference in this respect. Besides these, there are various minor points of comparison between the two gases, on which however, it is unnecessary to enlarge; and in regard to the advantage which oil gas possesses, of being more easily generated, and without any of those nuisances to which the coal gas establishments are subject, also its being less bulky, and held therefore in gasometers, and dis

tributed in pipes of half the usual dimensions, these advantages are all involved in the price.

Such, then, are a few of the facts regarding these two species of light, which we have endeavoured to collect, from different sources, for the information of our readers. It is evident, on the whole, that the oil gas, though it will be a much cheaper light than candles, will yet here be considerably dearer than coal gas; but then it is purer, and burns with a brighter light; and, as Mr. Dewey of New York remarks, if some are content with fine, there is no reason why others should not prefer superfine. This, of course, is a matter of choice with the public; and it is not our intention, by the above remarks, to recommend either the one or the other light in preference, but merely to state the facts which have come to our knowledge.-Cal. Mercury.

I AM fully convinced that Nova Scotia would be found possessed of as great a proportion of natural curiosities as any part of the continent of America, were it adequately explored; but few even of what have been discovered, have we on record; and even to our inhabitants, I have no doubt but that "the half has not been told." It is no less true than singular, that we often receive the first information of such curiosities as have been discovered in this province, from strangers-or in other countries. It was at all events the case with myself, in relation to the "Rocking Stone; whose existence I first heard of from a gentleman in the United States, who had inspected it with much admiration and astonishment.

A few days since, accompanied by a friend, I resolved to be personally satisfied of the existence and bulk of this "wonder of nature. We rode to Spryfield (the distance to which is probably six miles) and there left our gig.. Following a foot-path which led past the side of a small lake, we struck into the woods, and after walking about three quarters of a mile, and pursuing the directions we had received, we came to the spot. Its most interesting appearance is at first perceiving it.

It stands upon a flat stone, the surface of which is level with the ground. The rocking is effected by the aid of a short lever, and may be set in motion by a child of twelve years of age. Although it is very difficult to attain the summit, yet we succeeded, and felt very sensibly the rocking as we walked to and fro upon it. We examined it very minutely, and discovered this vast body to move upon a pivot in the centre, of about 12 inches by 6, and a slight rest at the north end. The quality of the rock is granite, but apparently somewhat porous. After rocking and inspecting this wonderful stone for some time, we proceeded to measure its size, which we found to be as follows:-20 feet in length -14 feet in breadth-9 feet thick, and the circumference 74 feet. Its motion is from E. N. E. to W. S. W. The place where the rock is situated is rather pleasant, being a plain, with the ground undu.. lary; and from its summit is presented to your view a beautiful lake, stretching serpentinely through the bushes. It is worthy of remark, that comparatively few stones appear in the neighbourhood of the rocking stone, and these quite small; so that no one can suppose it could by any accident have become disengaged from any large body of rock. It

is truly astonishing, and clearly evidences the skill and power of an Almighty hand! I broke off a piece for the purpose of ascertaining its weight, by which to form some idea of the number of tons contained in this rock. The following is a crude statement of

the result:-Its length being 3 inches -its breadth 24 inches-its thickness 2 inches, made 18 solid inches-and it weighed 1 lbs. The rocking stone, containing 2520 solid feet, makes its weight to be 162 tons. L. S. Halifax, August, 1823.

ON THE LONDON STREET. SIR,-In passing the Cross yesterday, I began out of mere curiosity to examine the progress of the building at the commencement of the new Street, and was very much surprised to find that it did not correspond with a very elegant deIsign given some time ago in your Magazine. Upon inquiry, I learned that that design had been abandoned, and a very different one adopted. I also learned that the design which had been adopted was to undergo some alteration, and that in the meantime, the building was proceeding very slowly. It is proposed that the corner of this Street, next the Cross, should be rounded off, but how much my informant could not say, as the affair had not been determined. Upon examining the present plan more minutely while on the spot, I saw plainly that a small rounding off would not obviate the difficulties and dangers which will inevitably present themselves whenever the new Road is opened. I beg, therefore, to call the attention of the public, and those concerned, to the following strong objections to this plan. Suppose that the London Mail comes flying along the new Road, and is about to enter the Trongate, the horses will have to make three turnings before they can fairly clear their way into the Trongate, and each successive turning will be commenced before the preceding one is completed, and that in such a narrow compass, as to endanger the lives of many of his Majesty's lieges, not only as coach passengers, but as humble pedestrians.

In coming out of the new Street into the Saltmarket, one turning must be made; but, there being no room for the horses to recover their rectilineal direction, on account of the short space between the opening of the new Street and the head of the Saltmarket, in going out of the latter into the Trongate, another

turning must be made, before the former is completed. In going into the Trongate while this turning is taking place, and before it is completed, a new one must be commenced, in order to avoid the statue of King William, against which the coach would be inevitably dashed, as it stands full in the way when turning the head of the Saltmarket. How much these turnings thus running into one another, and necessarily causing the jaded animals to pursue a serpentine course after a long stage, will endanger the safety of persons on the top of the coach, as well as the unwary foot passenger, who may be crossing the street at the time, and may be totally ignorant of the way he ought to run to avoid the danger, must be obvious to every one without comment. But how will the "confusion become worse confounded," and the danger indefinitely increased, when a coach shall happen to meet the mail at the turnings, while furiously driving in an opposite direction? Or when several vehicles shall meet at the turning points, from the Saltmarket, the Trongate, the High-Street, the Gallowgate, and the new Street? I believe there are few who would keep their seat in any one of the vehicles so circumstanced, without feeling a very considerable degree of apprehension. To many it would be positively alarming, and I think there is little wonder. The New Street Company would have avoided all these difficulties and many more which might be pointed out, had they adopted the plan given in your Magazine. They I would have had a beautiful crescent, where now they must have an ugly rounding off; and the crescent would have rendered only one turning necessary, and that in such an easy and gentle manner, that it would rather have been a relief to the horses than an exertion. How far it may be practicable to adopt it yet, ought to be considered, as there is not much above ground, and as it will be ul

ON DRESSING GOODS. SIR,-In Number XIX. of your valuable Mechanics' Magazine, I notice an improvement mentioned in dressing muslins, &c. by gas, and your Correspondent wishes to know whether there is a Patent for it or not. A Mr. Hall, of Nottingham, has obtained a Patent for dressing cloth with gas, and also a Mr. Burn, of Manchester, has taken out a Patent for an apparatus, by which he dresses all kinds of goods made of silk, cotton, woollen, or flax. I have seen both plans, and do assure N. P. they are very ingeniously contrived; yet of the two I think Mr. Burn's is better calculated for general use, being less expen.. sive and more simple, as he can use hot iron or gas, as may be convenient; and it may be set up in any bleaching works, &c. while that of Mr. Hall's can only be employed to advantage by such as dress for hire, as it will require a large capital to begin with; neither do I think Mr. Hall's method is well calculated for goods generally, as those which I have seen appeared very thin after being dressed. I would not have troubled you with this, had not your Correspondent wished for information; and as I constantly read your publication, if I could add any thing to it, I shall, at all times, feel great pleasure.

I am, Sir,

Your most obedient servant,

A FRIEND TO IMPROVEMENTS.

Chester, May 19, 1824.

We are much obliged to our Chester friend for his good wishes and willingness to communicate. We trust he will soon take an opportunity to do so, as a willing mind is the great desideratum; we wish that some of our friends at home, who we know are very able, were imbued with the same spirit. On the subject of this letter, we have received very important information, which we shall communicate perhaps next week.

WINDMILLS.

SIR,-In Nicholson's Encyclopedia, under the word "Mills," the following statement occurs:

"The simplest mode of constructing

a Windmill, is with a spiral sail, passing round a centre pole, tapering towards the summit, and spreading to a great width at the base. This certainly has not very great powers, but acts with great uniformity, and requires no attendance, since it matters not from what quarter the wind blows."

He adds that such a mill is cheap and safe, even in exposed situations. If any of the Correspondents of your valuable Miscellany have seen or heard of a Windmill of this description, and will give any information as to its construction, it will oblige a friend to your Magazine.

15th May, 1824.

QUERIES.

Z. A.

SIR,-In looking over the first Numbers of your Magazine, I observe an article in Number IV. which had before escaped my notice. It is concerning a meeting of the Highland Society of Scotland, when Mr. Dalyell submitted the models of various articles to the inspection of the Society; amongst other things there were mentioned an improved Row Boat, transmitted by Sir David Milne, and a Snow Plough, by Mr. Allan, at Pennycuik.

Will you, Sir, or any of your Correspondents, be so kind as answer the following Queries concerning these two articles.

1. Is Sir David Milne the inventor of the improved Row Boat, as it is only mentioned that he transmitted it?

2. In what respect does the improved Row Boat differ from other boats, and to what particular use (if any) is it to be appropriated?

3. In what part, or parts, of the Snow Plough, does it differ from the common plough now in use? And

4. Is it wrought like another plough, i. e. drawn by horses or oxen? And in what respect has it the advantage over the common plough?

A general description of these two articles, particularly answers to the questions, will much oblige,

D. A. N.

We join in our Correspondent's request; and we think the inventors would be the most likely to furnish appropriate answers. If, therefore, this should meet their eye, or that of any of their acquaintance, perhaps they would be kind enough to furnish the information wanted.

Lanterns.-M. Lariviere, a Mechanic at Geneva, has conceived the idea of substituting for glass in lanterns, plates of polished iron, pierced with small holes, regularly placed, and very close to one another. These plates allow the light to pass through them extremely well, and are much superior to metallic wires, which are easily deranged. The same person is at work upon a machine by which he will be enabled to pierce with regularity and expedition à number of small holes, so as to perform in a minute the same labour which, according to the existing methods, it would require an hour to execute. This invention will be very serviceable in the construction of sieves and filtering vessels.-Lit. Gaz.

To discover if Bread is adulterated with Alum.-The bread must be soaked in water, and to the water in which it has been soaked, a little of any test for sulphuric acid must be added. (Solution of muriate of lime will do.) Upon which, if any alum be present, the liquid will be pervaded with milkiness; but if the bread be pure, the liquid will remain limpid.-Rationale. Sulphuric acid has a stronger affinity for lime than for the alumina and potass with which it forms alum; it, therefore, quits those bodies, to form sulphate of lime with the lime of the test-which produces the milkiness.--Griffin's Chemical Recreations.

To distinguish a solution of Epsom Salt from a solution of Oxalic Acid.-1. Taste the solution; Epsom salt is bitter; oxalic acid extremely sour.-2. Pour a little tincture of litmus into the solution; if Epsom salt be present, the blue colour will remain unchanged; if oxalic acid be present, the blue will be turned to red.-3. Tincture of cabbage, or any other vegetable infusion, or a slip of litmus test-paper, are all acted upon by the acid, (which changes their colours,)

but not by the salt.-What a pity it is, that people should poison themselves by swallowing the acid instead of the salt, when the method of distinguishing them is so easy!-Ib.

Test for the purity of Magnesia.—The common magnesia of the shops (which is a carbonate) is frequently adulterated with chalk; this may be detected by adding a little diluted sulphuric acid, which, with magnesia, forms a very soluble salt, but with lime, a very insoluble one. Pure magnesia (called calcined magnesia, in the shops) dissolves in diluted sulphuric acid entirely, and without effervescence.-Ib.

Test for the Purity of Wine.-Put into a phial sixteen grains of sulphuret of lime, (prepared by exposing to a red heat, in a covered crucible, equal weights of powdered lime and sulphur) and twenty grains of super-tartrate of potass (cream of tartar.) Fill the phial with water, cork it well, and shake it occasionally, for the space of ten minutes. Separate the clear liquid by decantation, and preserve it in a well-stopped bottle for use. A portion of this liquor, fresh prepared, when added to wine containing lead, produces a blackish precipitate.-Ib.

Steinhauser's Method of Making Artificial Magnets.-Professor Steinhauser has found, that the usual operation of double touch should be performed in a circle; and that, in magnetising horse-shoe magnets, two of them should be placed with their friendly poles together, and the touch performed circularly. Upon the separation of the two horse-shoe magnets, a considerable part of their force is lost, unless the great circuit is previously formed into two smaller ones, by joining the poles of each with a piece of soft iron. By these rules magnets of extraordinary power may be made.-Edin. Phil. Jour.

J. CURLL, PRINTER.