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CIRCULATING DECIMALS.

and bringing down double the quantity of gas." If it brought down six times the quantity of gas, a proper well-managed quantity of air continually kept in motion round long-work, would have swept it away. But the yard or Bensham coal should be worked before the next under it.

I should very much like to know how Mr. Buddle's long-work was began; upon what plan it was opened; how wide and long it was when it grinded the coal to powder; whether the roof broke down at all behind him before he gave it up? I say nothing of the mode of working the thick coal in Staffordshire-that is not long-work; one thing only I would observe, some of the boys employed now on that magnificent vein of coal will be rummaging it over again for what is left behind by their present mode of working it. Mr. Buddle, speaking of the Bensham seam of coal, says, "I found it prodigiously fiery, so much so, that the coal itself afforded gas enough to light the pit. * Í drilled a hole into the coal, and stuck a tin pipe into it, and lighted it, and I had immediately a gaslight." Now, sir, that proves nothing at all extraordinary, because I have seen much greater intimations of fierceness than that, and the mine as sweet and clean of gas, at the time, as a house. have seen oftentimes, when the colliers have been making a cutting across the seam about six or seven inches wide and three feet into the solid coal, a lighted candle has been put into the cutting, and the gas would ignite immediately and fill the cutting with flame, which would frequently keep burning till it was brushed out. No one in the mine cared a fig for such incidents as this, because they knew a current of air was passing along the face of the work, which would not suffer the flame to come out of the cutting.

I

Mr. G. Mitcheson, on being asked if he thought the principle of long-work could be applied to the northern collieries, said, that"in many places in the North they had a post or stone roof that would stand forty or fifty yards upon an area; he did not think that long-work could at all be practised there, for it would never break down behind them, and there would be ten times more space for foul air than there is now."

According to this witness the stone roof will stand forty or fifty yards upon

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an area, but I should not call that long-
work; that is, stall and pillar work. I
have seen walls of coal worked 400 or
500 yards in length. Does Mr. Mitcheson
think the northern stone roofs would fall
in that length behind him? I know they
would, though I also know that a rock
roof is not the best roof for long-work.
The first sinking that takes place in long-
work, after a sufficient quantity of coal
is taken from under, to allow the strata to
settle down, if the roof is very strong,
shale or rock, often causes great confusion,
and a novice in the trade would be soon
inclined to abandon it. But an old long-
worker knows how to manage the weight
to his own advantage, ever after, in work-
ing the mine. Why did not the Com-
mittee procure
the opinions of some
Shropshire long-workers? In that district
the system of coal-getting is wholly long-
work, whether the roof be stone, clunch
clay, or even sand!

I am, your obliged servant,
THOMAS DEAKIN.

Blaenavon, May 5, 1836.

CIRCULATING DECIMALS.

Sir,-Your correspondent, G. C. L., p. 43, is somewhat hasty in his assertion, that I have taken but a partial view of the question I proposed and answered, on circulating decimals.

The rule I gave may be applied generally, though in some cases it requires a knowledge of several properties of circulates, some of which I referred to in my former communication. The ex

ample attempted to be worked by G. C. L. may be considered as one case of the rule, and that proposed by me as another, though this is almost a distinction without a difference; for, in his example, the 1 0584 +

denominator of the decimal is

=

=6 hence, the fraction is

17, as found by him and the numerator, 38235+ 05882+ 13 61 17 34'

The attempt to find the denominator by the part next in value, reminds me of the school-boy, who, if he obtain the "answer," heeds not how it has been procured.

In order to avoid complex fractions, if, by the first part of the rule, it is found

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that the decimal is a mixed circulate, the given part may be multiplied by that power of 2, the index of which is the number of terminate figures; this product, divided by the part of the least value, will give the numerator and the denominator found by the rule, being multiplied by the same power of 2, will give the required denominator.

It is with regret that I am forced to observe, that your correspondent does not appear to have sufficiently considered the subject; in the second paragraph he says, "if we take any numerator for the

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to the part therefore forming the circulate does recur with every multiplier.

Having adopted an original method for exhibiting the circulates of any fraction, which affords a ready means for examining their several properties, I subjoin the circulates of

a

as an example.

34

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1 | 27 | 15 |31|21| 23 | 9|5|33| 7 19 7 4 9| 6| 6| 2| 1 9 2 5 2 9 4

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6

0 5

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17ths.

1| 10 | 15 | 14 | 4| 6

9|5|16|7| 21 3

0 5 8 3 2 3 5

In these tables the upper lines are the numerators, or successive remainder, in finding the circulate by the common method; and the bottom lines the circulating series. The middle line is the terminate figures; these arise from all fractions whose denominators are divisible by 2, 2a, 5, 5", and they possess the same property as the series, viz. half being complements to 9 with the other half. By the arrangement, the commencing figure of the series is placed under its respective numerator.

When a is exhibited in the form of a

m

circulating decimal, a series of figures equal to m-1 is either produced, or two or more series, the sum of the figures in

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MORDAN AND Co.'s NEW PATENT PEN.

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sist of more than one series, each of which must be found either wholly, or in part, to discover where the series is of the least value decimally.

I have not had time to investigate the rules given by G. C. L., which may be correct, though the first one, upon which the others depend, has an inconsistency in its expression; for if 999, ad infinitum, is to be divided by the given number, there cannot be a last remainder : he probably means that the division is to be made until the figures recur; if so, it is fortunate for him that the answer to my question, which he has chosen to illustrate

his rule, happened to be

to the re

15 43

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MORDAN AND co.'s new PATENT PEN.

Sir, It is a great pity that patent speculators, before patenting a thing, do not give themselves the trouble to ascertain whether a similar production to it has been, in any shape whatever, previously before the public. The want of this very necessary precaution exhibits itself in the instance of the three-nibbed metallic pen, advertised in different journals, and exhibited (per engraved card) in various stationers' windows, as a recent patent of Messrs. Mordan and Co.

At p. 31 of a pamphlet on metallic pens, by J. Carstairs,* will be found the description of a metal pen, the invention of a Mr. James Gowland, chronometer

* Simpkin, Marshall, and Co. 1835.

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maker, 11, Leathersellers' Buildings, London Wall, answering precisely to the subject of the present comment. The hardship of individuals losing their inventions, through an incapability of ascertaining what had been before invented and privately made use of, has been altogether removed by the alterations in the law of patents; the public, however, have a just right to benefit by the oversight of patentees where the opportunity exists of information. It is a matter of surprise that gentlemen so long in the field of invention, and bona fide manufacturers into the bargain, as Messrs. Mordan and Co., should have put themselves to the expense of attempting to secure what appears to be nearly, if not quite, a year old.

Sir, your obedient servant,

SCRUTATOR (pro bono publico).

HANCOCK'S STEAM-CARRIAGES.

Mr. Hancock still continues to run his steam-carriages on the Paddington-road with uninterrupted success. No accidents have happened, nor any derangement of the machinery, unless the breaking of a chain pulley may be so called, which was immediately replaced by another. The "Infant," which Mr. H. yesterday (Friday) brought from Stratford, for the purpose of working on the Paddington-road, is the first steam carriage that ever ran for hire, which it did on the same road about six years ago, and a fortnight before Sir Charles Dance commenced running on the Cheltenham-road with Mr. Gurney's drag. The "Infant" seems in excellent condition, and apparently not any the worse for the occasional working it has had since its birth.

The rate of travelling during this week has been about the same as last; averaging one hour and ten minutes from the City to Paddington and back, a distance of nine miles. Of this time upwards of one-fourth is consumed in stoppages for coke, water, and passengers. From Monday morning, to Thursday 12 o'clock, sixteen single trips to Paddington were performed, and forty-six to Islington. The number of passengers carried was 711.

We understand the carriages will continue to run daily, in the morning from 9 to 12, and in the afternoon from 3 to 6 o'clock.

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NOTES AND NOTICES.

NOTES AND NOTICES.

Preservation of Animal Substances.-A pamphlet published at Florence gives an account of a strange discovery by Geralamo Legato, the accuracy of which is attested by the principal professors in that city. It appears that Legato, while traversing the deserts of Africa in 1820, for the purpose of perfeeting a map, discovered in one of the hollows which a whirlwind had ploughed up, a completely charred human body, the flesh and bones of which were in good preservation. It struck him that the process of charring could only be effected by the scorching sand, and that if the heat of the sand had in this instance effected the complete disiccation and carbonization of animal substances, it might be possible to effect something similar by artificial means. On his return to Italy, he commenced his experiments, and at length succeeded in imparting to the limbs and bodies of animals solidity, and indestructible durability. By this, whole bodies, as well as individual parts, acquire a thoroughly firm consistence, which is more decided according as the respective parts are harder or softer. The skins, muscles, nerves, veins, fat, blood, all undergo this change without its being necessary to remove the intestines, which assume the same consistence. At the same time the colour, form, and character, in general, remain unchanged; no smell is perceptible, and both joints and limbs remain flexible and moveable as when alive. When bodies have acquired this consistency, neither damp air, moths, nor water can effect them. The weight is but slightly diminished. Not a hair

is lost; on the contrary, they are rooted more firmly than ever. Birds and fishes lose neither skins, scales, nor colours, and in like manner insects and worms remain perfect in every respect. Legato's cabinet contains many specimens of this novel and singular discovery. One of the most re. markable is a table composed of 214 pieces joined together. The observer would take them for so many different kinds of stone, and yet they are nothing more than portions of the human members.Scotsman.

Colossus Redivivus.-An Englishman has lately erected on the banks of the river Theiss, in Hungary, a mill in the form of a colossal man. The head is the dwelling-house, the eyes serving for windows, and the nose for a double chimney. The machinery is placed in the body, and set in motion by a stream of water from a canal in the form of an immense bottle, which the monster is emptying into his mouth.-Times. How is the water raised into the bottle?-Q.

New Percussion Gun.-The Wirtemburg papers Occupy themselves much about experiments made with a percussion gun, of the invention of Duke Henry, by means of which an able soldier can fire eight or ten shots in a minute.

Wonders of Mechanism.-The Hague Journal states, that a Dutch artilleryman, named Vander Boll, having 1 st both his arms below the elbow, by an explosion, the sculptor, J. F. Freit, of Flushing, has contrived and executed for him two artificial fore arms and hands, with which he can feed himself, put on his clothes, perform all other ordinary offices, and even write. (?) The poor man was also deprived of one of his eyes, but for this we suppose no substitute can be found!- Guernsey Star.

Sampson Twigg and Co., a firm of three labouring men, obtained permission to work in a mine at Botstone, in this county, the property of Messrs. Gaunt and Challinor, of Leek, and to take the minerals, subject to a certain tribute to the proprietors, for six months to come. The mine is at the bottom of a stupendous mountain. The men began at the bottom of the hill, and after consider

able labour were able to strike through some coverings of flint, when they discovered a vein of ore, almost pure lead, and in three days have not raised less than three tons, worth 201. a-ton. It is expected, without exaggeration, that for six months to come they will gain 100%. a-week by their own manual labour, exclusive of the tribute payable to the proprietors; but fears are entertained that their good fortune may cause the death of some of them from over exertion, as they are not to have any assistance. Botstone is within half a mile of the famed Ecton mine, from which the Duke of Devonshire amassed so large a fortune; and what is very singular, these three men have been working at the first-named mine near one year, earning not more than 12s. each a week, and have frequently blasted within a yard of the place where the treasure has been discovered. The face of the vein is not six yards from the surface.-Stafford Paper.

Mr. Thomas Sheriff, Westbarns, East Lothian, has invented a plough, for which he has been awarded a premium of five guineas by the East Lothian Society. The property of this implement is to cultivate the subsoil, in opposition to the system of trenching, which was lately introduced into East Lothian, and the tendency of which was to turn down the rich vegetable mould, and raise up the subsoil, in many, nay, in most cases, always the inferior. Its construction is simple, and every common plough can be converted into a subsoil plough at pleasure, and at a trifling expense. It is only calculated to operate successfully on a subsoil whioh does not afford much resistance; but a plough has been invented in Stirlingshire, which, with a proper application of strength, will cultivate the most stubborn clay subsoil that exists.Farmers' Magazine.

Communications received from A SubscriberMr. R. Roberts-Mr. Lunt.

"An Old Subscriber" is informed, that we are always willing to publish the particulars of useful inventions without payment. His order on town for cash has been destroyed.

Errata.-In a few impressions of our last Number, p. 95, col. 2, line 8 from bottom, for "11," read "9,"-and line 6 from bottom, for " 11," read "12."

The Supplement to Vol. XXIV., containing Ti. tle, Contents, Index, &c., and embellished with a Portrait of Mr. Walter Hancock, C. E., is now published, price 6d. Also the Volume complete in boards, price 98. 6d.

Patents taken out with economy and despatch; Specifications, Disclaimers, and Amend. ments, prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterborough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion-square. Sold by G. W. M. REYNOLDS, Proprietor of the French, English, and American Library, 55, Rue Neuve, Saint Augustin, Paris.

CUNNINGHAM and SALMON, Printers,
Fleet-street.

Mechanics' Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

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