Sidebilder
PDF
ePub

METEOROLOGICAL JOURNAL FOR SEPTEMBER.

The first nine and the last five days of this month were dry, the other part was generally wet, yet the weather has been remarkably warm for the season, frequently sultry in the evenings and throughout several nights, insomuch that the mean temperature of the air this month is only 11-10th degree less than that of last month. The mean temperature of the external air this month is 3 degrees higher than the mean of September for the last nine years. The temperature of spring water arrived at its maximum at the time of the autumnal equinox ; and, in consequence of the dryness of the summer, and the unusually high temperature of the ground, its maximum for the present year is one-third of a degree higher than the mean of the maxima for the last five years. The steadiness of the mercury in the barometer at this period, arising from the gentleness of the atmospherical tides, as they are termed, is a proof the calmness of the weather. Should it be asked what this unprecedented mean temperature of the air is attributable to, we would answer,with deference, that it may have been influenced partly by the great heat of the ground, as ascertained by the temperature of spring water, and partly by the conjunction of the planets, as hereafter mentioned, and the recent appearance of the comets that are said to be pervading the solar sysFor we have particularly observed, that the temperature of the air is comparatively higher when a comet is present, than when it has receded from the sight; and by admitting the theory of attraction of the planetary bodies, and the diffusion of light and caloric to them as well as to our earth, it is not irrelevant to suppose, that the conjunction of an inferior with superior planets may have a tendency to increase, in some measure, the heat of our atmosphere. Such a suggestion is certainly deserving the attention of the philosophic mind, though we admit it to be a subject hitherto uninvestigated.

tem.

The atmospheric and meteoric phenomena that have come within our observations this month, are

443

three parhelia, one paraseline, two solar and two lunar lialos, one rainbow, and one lunar iris on the 25th, the latter at 9 P. M.; twenty-four meteors, lightning in the nights of the 11th, 14th, and 20th; and thunder in the afternoon of the 14th; three strong gales of wind, namely, one from S.E. and two from S.W., the first of which came on the day preceding the autumnal equinox.

Singular Appearances of Meteors.In the evening of the 4th instant, a large meteor passed from the star Alpha, in the constellation Aries, to the Pleiades nearly, and showed itself in this direction, mostly behind a wane-cloud.

In the evening of the 13th, at a quarter past nine o'clock, a brilliant meteor, of a whitish colour, in its descent from the star Atair, in Aquila, divided in two distinct parts just before it disappeared.

Conjunction of the Planets, &c.Soon after four o'clock in the morning of the 28th, a conjunction of the planets Mars and Venus, and the star Regulus was observed here. These celestial objects were about 15 degrees above the eastern horizon, in the prime vertical, and the sky being cloudless at the time, made this interesting phenomenon very conspicuous. The distance of Venus from Mars was 44 minutes of a degree, and from Regulus 39′ 5′′, all of them forming an isosceles triangle. Jupiter was 6° 33′ to the eastward of Venus; an occultation of Regulus behind Venus took place at six o'clock in the evening of the same day, and at 10 P. M. Mars and Venus were in their nearest conjunction, namely, two-thirds of a degree distant from each other.

At four o'clock in the morning of October the 4th, a conjunction of Venus and Jupiter was also observed here, when the former was distant from the latter 40 minutes. Venus, in this position, certainly appeared the most brilliant of the two, ad reflected a greater light upon th. Larth than Jupiter did. In the trening, Venus, when passing the southern side of Jupiter (although invisible to us), was only a few minutes distant from him.

444

VARNISH-MANUFACTURERS-PRINTING PRESS INDEX, ETC.

TENACITY OF IRON, AS APPLICABLE TO CHAIN-BRIDGES.

The following results have been deduced from experiments made in Russia, and detailed by M. Lamb, in a letter from Petersburgh, Ann. des Mines, x. 311. In the apparatus contrived for the purpose the power was applied by a hydraulic press.

The best iron tried supported 26 tons per square inch, without being torn asunder. The bars began to lengthen sensibly when two-thirds of this power had been applied, and the elongation appeared to increase in a geometrical ratio with arithmetical increments of power. The worst iron tried gave way under a tension of 14 tous to the square inch of section, and did not lengthen sensibly before rupture. By forging four bars of iron of medium quality together, an iron was obtained which

did not begin to lengthen until 16 tons had been applied, and supporting a weight of 24 tons without breaking.

Taking these results as sufficient data, it was decided by the committee appointed for the purpose, that the thickness of chains in a suspension-bridge should be calculated so that the maximum weight to be borne should not exceed 8 tons per square inch of sectional surface, and that, before being used, they should be subjected to a tension of 16 tous per square inch, and bear it without any sensible elongation.

HINT TO VARNISH-MANUFACTURERS.

SIR, A thought lately struck me, that a strong iron vessel (something like Mr. Perkins's steam-generator, but much less) might be advantageously employed in the manufacturing of Varnish. Amber and copal make the best hard varnish, but they are exceedingly difficult to dissolve, owing to their requiring a greater heat than turpentine or spirits of wine will bear without evaporating.. The latter, indeed, is so volatile, that I do not believe they were ever dissolved in it alone; and it is said, that only two or three persons in this

country can make copal varnish properly.

As water, when confined, can be heated to almost any degree, I see no obstacle to hinder us from heating the usual menstruums of varnish in the same manner. They are more volatile, but we have only to make the vessel stronger. The gums, no doubt, would be better for being crushed and mixed with the spirit, before they were put into the vessel. I remain, Sir,

Your obedient servant,
W

PRINTING PRESS INDEX.

SIR,-In Number 106, vol. IV., of your very useful Publication, I find counting the Number of Sheets an article respecting a Machine for pulled by a Printing Press. I beg

to I made a machine for that say, purpose some years ago, and I have a working model of it by me at this time. The description is as follows:

It counts from one sheet to any number required; and there is a bell strikes at any given number, which gives notice to the person number is complete. It is not newho takes off at the press that such a cessary this machine should be placed on the press, or in the press-room, as it will work in any part of the preabove will oblige mises required. The insertion of the

Your obedient servant,

Northampton.

[ocr errors]

J. SHARP,

[merged small][ocr errors][merged small][merged small]

"

THE RAZOR QUESTION.

centre of each pustule. M. Dumerel says that he has been long familiar with this practice, but, instead of the solution, he employed the solid caustic itself.

WHY DOES A RAZOR CUT BETTER AFTER BEING DIPPED IN HOT WATER?

SIR, I shall trouble you with a few remarks on Mr. Pasley's paper, which, perhaps, you may deem worthy a place in your valuable Magazine.

His first explanation, on the most cursory view, appears quite erroneous, inasmuch as the obstruction on the sand- paper is occasioned not by any imperfection in the scissars, but solely on account of the sand; so the obstruction to the razor is in the beard. We know that a razor would go over the chin smoothly enough if the bristles were not there to interrupt it-the comparison does not hold good.

Mr. Pasley next tells us that fire is not hot. He appears to be one of that fanciful class of philosophers who would wish to convince men, against the evidence of their senses, that the qualities of heat and cold exist not in bodies themselves, but are merely incidental sensations arising no one can say how. Might he not as well tell us that a steam-engine is not at work when no one is present to be a witness of its movements? The one position will hold just as good as the other.

Mr. Pasley would wish us to believe that fire is only hot when felt, an absurdity too palpable to need serious refutation. If Mr. P. intends to say that fire is not the essence of heat, he is right; but to say it does not convey the feeling called hot, is ridiculous.

To return, however, to the question, Why a razor cuts better after being dipped in hot water? I would beg leave, before entering further upon it, to ask how it has been ascertained that a razor does cut better alter that? This is, at present, a matter of doubt with me, for I know a very different reason why razors are dipped in water, which I may, with your permission, some day state; and, perhaps, the insertion of my inquiry will be the means of stopping a long and needless discussion.

I am, Sir,

Your very obedient servant,

T. M. B.

445

SIR, I am rather at a loss to comprehend the meaning of Mr. T. II. Pasley, when he says that "the razor, before being dipped, has obstructions in itself to overcome," and does not explain what these obstructions are. I conceive that he merely repeats, in other words,that razors cut better when dipped than when not dipped, which is the fact required to be explained. As to the long story of fire being hot or cold, I can only reply, that the word heat is used to convey the idea of the effect of fire, and therefore fire may be said to possess heat or to be hot, in spite of the nice and subtle distinctions of Mr. T. H. P. I faucy that, if he would hold his finger in a candle for a minute, he would soon become convinced of its heat, i. e. of the cause residing in the candle, which produced a sensation on the sensorium. But this is more addressed to the writer than the subject: 1 myself think that the heat of the water, causing expausion in the metal, tends to equalize the uneven edge, and thus facilitates the important operation of shaving. I am, Sir,

Your obedient servant,
Bingham.

IGNIS.

SIR,-The answer of your Corre spondent, T. H. Pasley, to the question of Novaculus, is, I think, a little far fetched. I have often thought on the subject, and have come to a conclusion that is quite satisfactory to my own mind; but if I should be wrong (which is not unlikely), perhaps some of your Correspondents will be kind enough to

correct me.

The microscope enables us to discover that a razor set with ever so fine an edge, is, in fact, a saw, and the edge, which appears so smooth to the is filled with teeth; now, ting of this instrument depends, as in

eye,

the cut

all other toothed instruments, on the sharpness and cleanness of the teeth.. A saw with a thick blade requires. great labour to make it cut, but this. labour is diminished in proportion to the thinness of the blade and the fineness of the teeth; but it is not only necessary, in order to its cutting smoothly, that the blade should be thin, but also that the teeth should be quite clean, and this is rendered niofe and more necessary as they decrease in size, so that, if the teeth are very small, the least thing will clog them up, and recourse must be had to some

446

THE PERPETUAL MOTION SEEKERS.

means of clearing them. Now, if this reasoning is applied to the case in hand, I think it may be easily seen that an accumulation of fine particles of dust, some little remains of soap, and a trifling corrosion of the steel, will be quite sufficient to retard the cutting of a razor, although the razor may be sharp, and in this case I think nothing is likely so effectually to remove these substances as immersing the razor in boiling water; but hot water will not always clear the teeth, so that we are obliged to take the strap, and when neither hot water nor the strap will effect it, the edge is become thick, and recourse must be had to the hone.

Many people (and I think some of your Correspondents) seem to imagine that a bit of leather, after being rubbed with pewter, or a bit of cotton cloth, or an old stocking, contributes to the sharpening a razor, by acting in some minute degree in abrading off or reducing the thickness of its edge; but this I think is a great error-the hone, and nothing but the hone, makes the edge thin and produces the teeth; the strap and the hot water clean out the interstices, and they do no more; at least this is my opinion. Perhaps trying the razor with a dry heat would decide the question.

I am, Sir, Yours respectfully,

SAMOHT.

known people who either could or would not be convinced of the fallacy of a favourite project but by expe riment.

I am at issue with P. M. as regards his little device acting for a time-it would do no such thing; for how, in the name of wonder, could the ball which escapes round the corner, force itself from B to A without lifting the whole column of water contained in that leg, as the ball and tube are represented of the same diameter? Talk of preposterous, indeed! Here the word is explained in perfection.

I now take my leave of P. M.'s. "little device" and " very small valves, and next of their inventor, whom I can assure, without chaffing, that he has not given me the slightest offence either by the excellent pun respecting the "mighty Tom," or by the numerous extracts which he made from my paper, and fitted so expertly and judiciously into his text. I have only got one fear, that in consequence of his expressing so much warmth at being styled a young man, people may get into the other extreme, and set him down for an old woman.

Sir,

I once more subscribe myself "under the name" of

T. BELL.

Commercial-road, Whitechapel, October 10, 1825.

THE PERPETUAL MOTION SEEKERS. SIR,-Your Correspondent, PhiloMontis, has rung me such a peal, and so belaboured me with my own cudgels, that I declare I have not yet recovered from that state of vibration consequent on such an attack.

66

Now, Sir, as regards the motive which is so 66 very apparent," and the "cocks and springs," which I never mentioned a syllable about, can any one for a moment suppose, that after stating the defect of P. M.'s "little device," I should, at the next breath, attempt to build a great" one upon the same rotten foundation? My intention was merely this, to furnish a simpler and less expensive mode of applying the same principle, and thus afford to any reader of the Mechanics' Magazine who might be unacquainted with the laws of fluids, &c. an opportunity of satisfying himself, by actual construction, of the inadequacy of the means to the end proposed, for I have

FIXING CRAYON COLOURS.

SIR,-The method given in page 381 of your 108th Number, for fixing crayons, might, and certainly would, "fix" them permanently; but from all that I have proved of the method offered (and I have used crayons forty years), I am so far authorised to tell you that the colour-' ing (which is the main object of using any kind of paint) would be too much changed, especially the high lights, so as to render the method hurtful. I have frequently inquired into these sort of expedients, and, without one exception, have been answered, "it certainly will render the picture durable, but spoils it."

I am, Sir,

Your most obedient servant, CHARLES HAYTER.

INQUIRIES-ANSWER TO INQUIRY.

[blocks in formation]

No. 160.

447

STEAM POWER REQUIRED TO RAISE WATER FROM THE THAMES TO PRIMROSE-HILL.

SIR,-It appears by a statement in one of the public Papers, that it is in contemplation to erect new water-works in the vicinity of Hammersmith, and that the reservoir of the same is to be on Little Primrose Hill, near Hampstead, and that the main pipe will be seven miles long, and will contain 1100 tons of water. I should feel obliged if one of your mechanical Correspondents would inform me (through the medium of the Mechanics' Magazine) what would be the power of a steamengine capable of raising the above quantity of water such a distance, supposing the acclivity from the inlet at the Thames to the reservoir to be 130 feet?

By giving the above a place in your truly valuable Magazine, you will very much oblige,

Sir,

Your obedient servant,

A MEMBER OF A MECHANICS' INSTITUTION IN KENT.

JW- ANSWER TO INQUIRY.

EMISSION OF LIGHT BY MERCURY.

SIR,-If a thin deal stops the opening on the top of an exhausted glass receiver, and mercury be poured on it, it will be forced through, and will fall into the receiver in a fine shower; and if the experiment be made in the dark, the shower will appear luminous. Now, how does mercury, in this instance, happen to give out light? If a bright metal is found to be made luminous by being agitated in vacuo, it will be important, as it will give us reason to suppose the heavenly bodies emit theirs on the same principle.

I am,
Sir,
Your obedient servant,

J-W

NO. 157.-MAKING BRONZE.

SIR-In answer to Inquiry No. 157, in your interesting Magazine, Number 110, I send your Correspondent, "H. S.," the very best method of making Bronze, which I have used for several years. Take spelter, and let it stand in spirits of wine for 24 hours; then pour off the solution, and let it evaporate, and boil it with three ounces, by measure, of sintum off, and strain it through a fine rag, senega, for two hours; then take it which will detain the fine powder, to be well washed with clear water, previous to using. The method of darkening the bronze is by simply adding chloride of ammonia, mixed with asphaltum; the mixture to be applied while hot to the brass or cop

« ForrigeFortsett »