Page images
PDF
EPUB

[ocr errors]

ON DYNAMITE.*

BY MR. A. NOBEL.

that they would blast with nitro-glycerine, even if they could get gunpowder for nothing.

87

The

simple investigation. Nearly all the calamities caused by nitro-glycerine have, in my opinion, beon owing to leakage, which, for practical reasons, it is I have been frequently asked for a positive stateCIENTIFIC and other papers have lately given directly chargeable to its liquid state. A substance of dynamite effects. This, however, is a question very difficult to prevent, and are, therefore, in- ment as to the economy in labour which the use much attention to a new blasting agent named sensitive to concussion, unless it is quite un- which cannot be answered in a positive manner, "Dynamite." It is nothing but nitro-glycerine manageable, like chloride of nitrogen, can easily for every kind of rock would require a special absorbed in highly-porous silica; and if I have be protocted against accidents by wrapping it in estimate, based on its hardness, the nature of the given it a new name, it is not by way of disguise, a soft material, but if that substance is a liquid strata, &c., and which greatly varies not only in but its explosive powers are so much altered as and a leakage takes place, it becomes subject to different localities, but within the limit of a single fully to warrant a new denomination. Dynamite the danger of direct percussion; and if nitro- mine. consists of 75 per cent. of nitro-glycerine, and glycerine in that condition becomes exposed to the Everyone will, therefore, have to form his 25 per cent. of porous silica. Hence it appears to sun's rays, the heat which it takes up renders it ascertain, the use of dynamite and nitro-glycerine own estimate; but as far as I have been able to possess only three-fourths of the power of nitro-so sensitive as to become dangerous under the generally cause a reduction of at least one-third glycerine, the specific gravity of both substances being very nearly the same. slightest blow. But practically there on the general cost of blasting, which is a very is no advantage in the greater concentration of From the beginning I have given special atten- great saving indeed, considering that the cost of the power of nitro-glycerine. It cannot, or at least tion to the packing of nitro-glycerine, but much explosive rarely figures more than 10 per cent. of ought not to be poured direct into the bore-hole, to my regret I must say that it is as yet far from the expense. I am, however, not in a position to since it easily causes accidents by leakage into satisfactory. Casks are not tight enough for oily give on this subject as full information as I might crevices, where it explodes under the miners' tools. liquids, and the property of nitro-glycerine to desire. The miners are generally extremely sparIt must, therefore, be used in cartridges, which expand when it congeals has obliged me to resorting in communications of that kind. Amongst my leave considerable windage; whereas dynamite, to square tins. These are left unpacked in the correspondents I can find only one who gives a clear being somewhat pasty, easily yields to the slightest factory for a month at least to ascertain whether and positive statement in figures of the saving pressure, so as completely to fill up the sides of they are tight, yet I can scarcely remember a effected: it is Mr. Alexander, manager of the the bore-hole and leave no windage whatever. single instance of a cart or cargo of nitro-glycerine is dated Feburary 2, 1868, and the mine up to that Phoenix mine, on the Lake Superior. This latter For this reason a given height of dynamite charge having reached its destination without a case or in a hole will contain quite as much nitro-glycerine more of leakage. The reason is probably to be tiine used 7,000lb. of nitro-glycerine (they have as when the latter is used in its pure liquid stato. found in the pressure to which the tin becomes no dynamite yet), so that the result is certainly It is necessary, even at the risk of some lengthi-exposed when the air which is confined inside, as based on sufficient practical experience. ness, to make this point clearly understood, for if well as the nitro-glycerine, becomes expanded by material had been purchased from New York at the advantages otherwise desired from the trans- an increase of the external temperature. What-the price of 1 dollar 50 cents per pound, irrespecformation of nitro-glycerine into dynamite were ever be the cause, it is certainly wrong to lay the tive of the cost of transportation to Lake Superior. obtained at the expense of a great depreciation of its blame on nitro-glycerine, for what has been due denfelt, director of the Great Northern Railway in Another statement of figures is that of Mr. Norpower, the substitute might be a safe but not a only to a practical difficulty. Let us suppose, for useful one. As it is, the block of wrought-iron instance, the case of gunpowder being transported Sweden, who, as far back as July 19, 1865, asserted here deposited will bear testimony to its great in casks dropping continuously out part of the that the use of nitro-glycerine had allowed his conpower. It was originally a cylinder of 11ft. dia- contents. A missing accident would almost be a tracting for blasting with a reduction of 25 per meter and 12ft. height, of best scrap iron, and cut rarity, and it is really a proof of the safe proper-glycerine an extensive tunnel through Stockholm, cent. Mr. Unge, who has blasted with nitrooff from a shaft. The bore-hole through its centre ties of nitro-glycerine that accidents have occurred was exactly lft., and the charge of 6oz. was put in almost only on those occasions (as at Aspinwall states the saving to have been 23 per cent. on the without securing either end by any sort of plug or and San Francisco) when it was forwarded under cost of blasting, and the progress of the tunnel tamping. The cylinder was blown at Merstham a wrong declaration, and, consequently the necesper cent. quicker than when gunpowder was on July 14, in the presence of a large audience. sity of cautious handling could not be known. used. These results show that, even in the present Allowing for the hole, and putting the tensile These hints will give sufficient insight into the state of comparative inexperience in the use of the strength of the iron at twenty tons per square importance of converting nitro-glycerine into a new explosive, a great economy is obtained. The inch, the strain necessary to effect the rupture must solid. It is not only a theory or some demonstra-saving of labour which dynamite causes is its have been equal to 2,400 tons; and since there tive experiments on which I base that assertion, greatest feature. Next to that we must class the was no plug at either end of the hole, it is evident but also on practical experience. Dynamite has saving of time. Nearly every mine is dependent that the charge was too much for the work only recently grown to be an article of commerce, railway tunnels, the famous one through Mont on the progress of its shafts and pits, and as for Besides blasting the cylinder, it had hurled the yet the quantity sold hitherto exceeds fifty tons, Cenis is only a glaring example of the necessity of one-half here deposited with such violence against and the most serious accident it had caused was a three-quarter boiler plate at some distance as to the case of a man who, having lighted the fuse, quickening the tedious work. Next to the saving break it. No wonder that a substance which tells kept the cartridge in his hand till it exploded and of time ranks its peculiar adaptability of wet so well on iron should be effective against rock. blew off his arm. No explosive can be safe against ground, since water has no effect on the charge. Coupled with this great power is a safety for proofs accidents of that kind. Besides the security do- Every miner has had more or less experience how of which I will simply refer to the test publicly rived from its solid form, dynamite has over nitro-difficult it is to blast with gunpowder wherever the made both at Glasgow and Merstham. A box conglycerine other special advantages. Its sensitive- Another sterling advantage of dynamite is that it rock is water-bleeding, which is only too common. taining about 81b. of dynamite (equal in power to ness to concussion is, as I have already stated, re801b. of gunpowder) was placed over a fire, where duced in a very high degree; and since fire does with a great number of minor accidents, which are needs no tamping, and consequently does away it slowly burned away; and another box with the not cause it to explode, it offers great security for little thought of in general, being too common to same quantity was hurled from a height of more transportation and stowage. Besides, it is quite be reported in the daily papers, but form, neverthan 60ft. on the rock below, no explosion ensuing natural that miners should prefer, as more prae-theless, a very long and sad list of continued tical, a solid to a liquid explosive. Dynamite is nearly all the workman has to do is to put them of that county are due to the act of tamping. It is now generally sold in ready-made cartridges, and calamity. I was told in Cornwall that by far the greater number of accidents occurring in the mines in his bore-hole and fire. abuse, I admit, for a hole may be tamped without Having now compared the two explosives, nitro-firing the charge, still it is very desirable to proglycerine and dynamite, and shown the reasons vide against a source of accidents, which, after why the latter, with equal power, is far superior to centuries of experience, still continues to exact so the former in point of safety and facility for use, I will briefly point out the sterling properties numerous victims. which render nitro-glycerine such a highly valuable blasting agent. essentially the same, so that what is said of one is The merits of dynamite are in the same measure applicable to the other. The miner's work is divided into two parts, viz., to make a chamber for the explosive, and to charge it. If that chamber was a matter of small expense, it might be very immaterial whether the amount of power required to do the work occupied a great or small bulk. But drilling holes in any rock, and especially in a hard one, is a slow and tedious labour, and there are mines where it takes a man three days' hard work to make a 1-inch bore of only 24in. in depth. Three days' labour, exclusive of tools, represents at least 9s., yet the charge of gunpowder which can be lodged in such a hole is at most Goz., or a value of less than 2d. It is easy, from such an example, to see why the miners should be anxious for a more powerful explosive, and ready to pay a much higher price for it. The instance here given is almost an extreme one, yet, even in rock of very little hardness, the cost of labour always greatly exceeds the value of the explosive used. It needs no explanation why an explosive containing, within the same bulk, ten times more power than gunpowder should greatly reduce the number of boreholes, and warrant a common saying amongst the workmen in Sweden

from the concussion sustained.

from a blasting material in order to be called safe; It is difficult to see what more can be required but some experiments made lately at Stockholm have put it to a still more severe test. A weight of 2001b. was dropped from a height of 20ft. on a box containing dynamite, which it smashed of course, yet no explosion took place. An account of this experiment is to be found in the Stockholm paper, "Afton Aladit," of this month. Such a test can leave no doubt that dynamite offers sufficient safety against concussion for all practical purposes, and we may say, as a Prussian military commission recently reported, that it appears to be the safest of all known explosives.

To those not fully acquainted with the nature of nitro-glycerine it seems puzzling that a mere absorption should be sufficient to produce such a radical change in its essential properties, but when we come to examine the matter closely it is easily accounted for. The greatest and almost the only drawback on nitro-glycerine is its liquid form. Much as has been written on the danger of congealed nitro-glycerine, I can confidently assert that if the solid form was its natural stato at the ordinary temperature, we should hardly have had to deplore a single one of those fatal accidents which it has caused. Moreover, it is a very erroneous notion that crystallized nitro-glycerine is more sensitive to concussion than the liquid one; the reverse is the case, and in a very remarkable degree; but that is immaterial to the present question, and only mention it to show how fancy notions take root and defy even the plain truth of

* Read before the British Association.

+ See MECHANICS' MAGAZINE for July 17, 1868, p. 41.

here set forth if, as has been sometimes asserted,
It would be a great drawback on advantages
a noxious nature.
the fumes of nitro-glycerine or dynamite were of
those who maintain that opinion is, that a great
The best answer, perhaps, to
number of mines are daily using it for underground
work, and that the miners do not at all complain.
The truth is, that when nitro-glycerine is allowed
to leak into the crevices of a bore-hole, it does
not all explode, and being dispersed in the at-
mosphero, causes a severe headache. It is, how-
ever, easily remedied by using cartridges, which
prevent leakage, and in the case of dynamite,
which is a solid, that inconvenience falls away
entirely. Since that explosive became introduced
in many mines assert that dynamite cannot bə
no complaints have been made, and the workmen
nitro-glycerine, because the fumes are so different.

will examine the practical results. The introduc-
So far as regards its properties. And now we
tion of dynamite is so recent that its advantages
over other blasting agents cannot be proved by
statistics; but in all excopt danger it is so analo-
gous to nitro-glycerine, that the results obtained
mate of its commercial value. Sweden is the only
with the latter will allow us to form a clear esti-
country where nitro-glycerine has been in use
ever since 1865; it is, therefore, the most con-
clusive example. The sales in that country, as

estron country, nitro-glycerine, notwithstanding the strong dislike which generally prevails against it, has been constantly used in the quarries of North Wales since 1866, and is in high favour with the miners. Two quarries alone (Brynderven and Driwrwic) have, up to this time, consumed about £3,000 worth of the material, or about nine tons; and its remaining stationary in North Wales is owing only to the circumstance that the manufacture and sale of the article has not been in this country, as in Sweden, an organized business. The workmen in Wales pay for the material which they consume, the price of 3s. 3d. per pound, while gunpowder costs only 44d., and if they continue to do so for years, it proves that they derive a benefit from its use. Still, a slate quarry is far from showing it at its greatest advantage, which can only become prominent in hard rock. Whatever success nitroglycerine has realized, it will certainly be admitted that it is not due to popular favour. No improvement has ever worked its way under a more crushing weight of opposition, and the very fact of its having stood it, is, perhaps, the best proof of its valuable properties. Gun cotton, which has been repeatedly pushed since more than twenty years, has not been used for blasting in all that time as much as nitro-glycerine in six months. Why? Because the miners had no advantage at all in using it.

ON THE SUPPOSED INFLUENCE OF THE
MOON ON THE TEMPERATURE OF THE
ATMOSPHERE NEAR THE SURFACE OF

THE EARTH.*

BY JOSEPH BAXENDELL, F.R.A.S.

Days after New Moon. Mean Temperaturo. 5th day

6th 7th

8th

9th

[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]

38-32deg. F.

38.30

38.57

38-16

37.65

:-

extracted from the books of the Nitro-glycerine is gradually decomposed, deposing oxalic acid, gave the same value of the temperature period, yet Company, at Stockholm, were, in 1865, 32,258lb.; while such a change has never occurred in the the epochs of maximum and minimum often differed in 1866, 48,785lb.; in 1867, 76,575lb.; and during same article manufactured on a large scale. With very considerably, thus indicating that the variathe first six months of the present year reached suitable apparatus, it takes less than an hour to tion was not due to any direct action of the sun, 64,293lb. These figures show a steady and rapid completely neutralize a ton of nitro-glycerine; and the effects of which would have occured simulincrease. The quantities are not enormous, but as a farther control, a small quantity of every taneously at all the stations. it should be borne in mind that Sweden, although day's produce, after it has been well mixed so as The adoption of any fixed value of a teman extensive country, is not a very productive one, to be fully uniform, is sealed and kept for inspec-perature period, whether that of the sun's geoand that Cornwall alone consumes three times as tion. That practice has now been carried on for centric rotation on his axis, or of the moon's much gunpowder as the whole of Sweden. The eighteen months, and shows not the slightest synodical revolution round the earth, or any assale of 221,900lb. of nitro-glycerine in that country, vestige of decomposition in any of the numerous sumed period, did not satisfactorily represent obequal to at least two and a-half million pounds samples. Having to store large quantities, not servations made in different years, and gave much of gunpowder, is therefore a proof of decided suc-only in six factories, but also in numerous depôts, greater probable errors than a variable temperacess. If the material had over gunpowder the it is but natural that I should have been anxious ture period whose changing values followed the advantage of cheapness, weight for weight, the myself to investigate the matter. In the case of course of the curve of sun spot frequency; and demand might possibly be ascribed to futile and dynamite, it is true that spontaneous combustion thus while the results given by the Astronomer mistaken economy; but as one pound of nitro- could mean only its catching fire and burning Royal in the Astronomische Nachrichten," No. glycerine costs the miners as much as eight pounds without explosion, since internal or external heat- 934, do not support the hypothesis of a temperaof gunpowder, it is evident that it must do some ing must naturally have the same effect; still, ture period depending on the sun's rotation on his work, or he would not have it. It has, no doubt, spontaneous combustion, even where no explosion axis, they will, nevertheless, on careful examinagreatly facilitated the introduction of nitro- can ensue, is a serious evil. tion be found to indicate changes of temperature glycerine in Sweden, that the transportation, occurring in a period which was gradually distorage, and use of the quantity above mentioned, minishing from the commencement of the series of has caused no accident of any serious nature, and observations in 1848 to its termination in 1853. positively a less total of minor accidents than if On the other hand, Mr. Harrison's results appear gunpowder had been used in its stead. That imto support very strongly the hypothesis of a lunar munity from danger is, in all probability, due to period; but it is easy to show that they form no the colder climate of Sweden, which allows of nitroexception to the same general law. For this purglycerine being transported, nearly all the year pose I have made use of the St. Petersburg obserround, in a congealed state, its freezing point vations for 1856-64, being the years comprised in being as high as 50deg. Mr. Harrison's Oxford series; and as the diagrams THE January number of the "Monthly Notices" which accompany Mr. Harrison's paper show a of the Royal Astronomical Society contains a maximum of mean daily temperature on the 7th paper entitled "Inductive Proof of the Moon's day after new moon, and a minimum on the 5th Insolation," by Mr. J. Park Harrison, M.A., in day after full moon, I have aranged the St. Peterswhich the Author points out that when the mean burg mean daily temperatures for the five days daily temperatures at Berlin for the years 1820-from the 5th day to the 9th day after new moon, 1835; at Oxford for 1856-64; and at Greenwich and the five days from the 3rd to the 7th after full for 1841-47 and 1856-64, are arranged in tables moon in two tables. There were 111 lunations according to the age of the moon, they show that a during the nine years, and the mean temperatures maximum mean temperature occurs on the average, of the selected days were found to be as follows:at each of the stations, upon the 6th and 7th day of the lunation, when the moon's crust turned towards the earth is coldest; and a minimum mean temperature some time after full moon, when the same crust has been exposed for several days to intense radiation from the sun. It does not appear that any other period than that of the moon's synodical revolution was tried; nor is any allusion made to the temperature period which, as Nervander and Buys Ballot showed many years ago, depends apparently upon the sun's geocentric rotation on his axis. The existence of both these periods has however been questioned. Thus Buys Ballot, on tabulating a series of 70 years' mean daily temperatures according to the moon's age, found that the highest temperatures occurred during the seven days after full moon, or precisely during that part of the lunar period in which, according to Mr. Harrison's results, the temperature is at a minimum; and the Astronomer koyal, The temperatures of the days in the group discussing the observations of temperature made after new moon are all below the lowest in the at Greenwich from the 2nd of June, 1848, to the group after full moon; and the mean of the first end of 1853, with reference to the period of the group is 1-11deg. below that of the second; but at sun's geocentric rotation on his axis, obtained a Oxford, during the same series of years, the series of numbers "which did not appear to sup-highest temperatures occurred on the days comport the hypothesis that there is any certain inequa-prised in the first group, and the lowest on those lity of temperature depending on the meridian of in the second. It is evident, therefore, that Mr. the sun which is turned towards the earth." Harrison's results cannot be regarded as a proof of In an inquiry of this nature it is, however manifestly very undesirable to rely upon observations taken during the same series of years at places so near each other as Greenwich and Oxford, or upon those taken at places far apart, bnt in different years. The general agreement between tho results of the Berlin observations in 1820 to 1835, and those at Oxford in 1856 to 1864, as given by Mr. Harrison is, of itself, no proof that the temperature of the earth's atmosphere is sensibly affected by the moon. This agreement may, and indeed does, arise from causes altogether independent of any influence of the moon. In a paper which I communicated to this Society in March, 1864," On Periodic Changes in the Magnetic Condition of the Earth, and in the Distribution of Temperature on its Surface," I showed that different years have temperature periods of different lengths ranging from about 23 to 31 days, the minimum values occurring in years of minimum solar spot frequency, and the maximum in years when the solar spots are most numerous; the approximate mean value as derived from observations made at various stations in Europe, Asia, and North America, during the years 1833 to 1859, being 27-4 days; and it was also shown that although in any particular year observations at places scattered widely over the three Continents,

In mentioning gun-cotton, it is but just to state that it has been highly improved of late by Professor Abel, I believe, and is sold now in a condensed state, in which it forms a good blasting agent, and ranks as such next to dynamite. Only a few years ago, the attempts which I witnessed to make gun-cotton take the place of gunpowder appeared to me to be perfectly fruitless. Bulk for bulk, it had less power, and that power was even more expensive than the power which it was meant to supersede. A new explosive cannot be introduced when the economical advantages are on the wrong side, and is next to impossible to get it adopted by miners unless the advantages are very great, and of a passable nature. But compressed gun-cotton is decidedly superior to gunpowder as a blasting agent, and if it cannot compete with dynamite, it is only because the manufacturing cost of the latter is less, while it possesses at least three times more power, and effects a far greater saving of labour. Details are only a matter of time and improvements, while the intrinsic merits of a substance decide the place which it is to occupy.

I know nothing, with the exception of, perhaps, a liability to spontaneous combustion, which could possibly warrant the absolute prohibition of a substance. Now, as for nitrated organic compounds in general, it is a decidedly erroneous notion that there is any such drawback attached to them. That notion has sprung up in laboratories because the chemist has no suitable means at hand for thoroughly neutralizing the adhering acid. It is well known that the continued action of nitric acid decomposes nearly every organic compound. It is, therefore, clear that unless nitrated compounds are rid of adhering nitric acid, they will decompose chemical in course of time. Hence we read in nearly every work, that nitro-glycerine

Literary and Philosophical Society.

Mean............... 38.20

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

the moon's insolation; or that it has any sensible effect upon the temperature of the atmosphere near the surface of the earth. I may here remark that the results given by Mr. Glaisher, F.R.S., in his paper "On the Iufluence of the Moon on the Direction of the Wind," are also dependent upon the general law above referred to, and cannot fairly be regarded as proving that the moon has really any influence upon the direction of the wind, since in most years, other periods than that of the moon's synodical revolution give greater differences in the distribution of the winds than can be obtained by employing the lunar period.

almost daily illustration. A fearful accident, resultTHE dangerous properties of petroleum receive ing from its incautions use, occurred on Monday night on the Cork and Queenstown Railway, near Fota. It appears that some repairs now being executed at a viaduct there are carried on at night, so as not to interfere with the traffic, and the workmen are provided with paraffin lamps. Three men were engaged filling several of these lamps, when a spark from a smouldering wick fell among some of the oil which was spilled on the ground. The fire spread rapidly, and soon reached the cask from which the supply of oil was being taken, and which was most incautiously left unprotected. It at once exploded, and the three men were so severely burned that their lives are depaired of.

STEAM HOISTING

APPARATUS AT
HANBURY'S WHARF.

BY MR. ARTHUR JACKSON.

meter. It is placed in a small house on a level with the top floor between the A and B warehouses. Beneath is the furnace, containing a series of gas burners, all of which when lighted will raise steam to 50lb. from cold water in twenty-five minutes. Steam being raised to the required point, the burners are extinguished, with the exception of one or two (which are sufficient to keep the pressure gauge stationary) until power is wanted, when instantaneously the furnace is fully kindled and the engine set in motion. Such is the immediate command over the boiler, that one moment steam can be generated at the rate of 61b. or 71b. per minute and the next the pressure gauge will remain stationary. The engine is erected on a tank containing 250 gallons of water. It has a cylinder 7in. diameter and 18in. stroke, and works direct on to the driving shaft, which is 85ft. long and works four sack tackles. The arrangement of the machinery, which is made by Mr. Thomas Middleton, of Loman-street, Southwark, is very good, and the whole is beautifully finished. The lift is 65ft., and more than 500 chests of tea are raised per hour. We cordially congratulate Mr. Jackson on the success of his gas furnace, and trust that many will follow the example of the Dock Company, and thus mitigate the constant inconvenience caused by the delay in discharging goods in the overcrowded streets of our large commercial cities.

[graphic]

DETACHED GRAVITY ESCAPEMENT.*
BY MR. H. KERR.

I maintaining impulse and the unlocking resistance

N this Detached Gravity Escapement both the

are uniform and perfectly independent of variations in the force of the train. A is the pendulum, which is composed of two steel rods extending nearly its whole length, and connected by traverse pieces. The escape-wheel is 2in. in diameter, has

IT

JACKSON'S GAS FURNACE.

liness, economy, and simplicity. The fire in
surance companies will admit them without extra
premium, so that steam may now be used where it
was previously prohibited. Moreover, there is no
smoke; that nuisance is, therefore, avoided. The
cost of keeping up steam to 50lb. pressure during
the intervals between work is practically nil, a
single jet sufficing for that purpose. For sim-
plicity it cannot be surpassed by any other steam
engine, as it does not require skilled labour, an
ordinary attendant sufficing to work it.

M

T is now about eighteen months since we noticed the introduction of Mr. Jackson's method of generating steam by gas into public use. Since that time we are glad to say Mr. Jackson has erected several of his gas furnaces in various establishments in London. Some of these we have described, but as yet we have illustrated none. fifteen teeth in its periphery, and fifteen short small We therefore take the present opportunity of steel pins set perpendicularly to its plane; see S. placing before our readers an engraving of a very The pins' circle has a radius of about in. The complete steam hoisting apparatus lately put up An apparatus of the same kind as the foregoing escape-wheel is placed at the bottom of the moveby Mr. Jackson at Hanbury's Wharf, Upper has just been erected by Mr. Jackson at the Cutler-ment and very near the back of the front frame. Nearly all the other parts of the escapement are Ground-street, Blackfriars. This arrangement, as street warehouses belonging to the London and with the pendulum, placed in front of the frame. will be seen from our engraving, is very compact, St. Katherine Docks Company. Steam has An arbor, borne by a cock in front and another beand occupies the least possible space that a steam hitherto been prohibited here-as, indeed, it has tween the escape-wheel and frame, has a short arm, engine could. It consists of a 2-ft. diameter been in many other cases-from the vast amount of or lever, which lies across the lifting pins. vertical tubular boiler heated by gas jets beneath. valuable property perpetually in store. Now, how-arm D is formed like a crank to allow it to pass the Steam is supplied at 50lb. pressure to a 6-inch ever, the fire insurance companies having approved inside cock and lie as close as possible to the wheel, cylinder having a 10-inch stroke, which drives the of Mr. Jackson's apparatus, permits its use without which allows the pins to be advantageously very hoisting apparatus. The gas is mixed with air extra premium. The engine in question has been short. The arbor, the pivots of which are conical before it is burned, so that complete combustion erected to supply lifting power to the eastern area and bear in drilled tempered screw points, has also results, and an intense heat is developed. The of these extensive buildings, and, now that its suc- two other arms, one of which, I, is the gravity impulse consumption of gas with this engine is from cess has been so fully proved, we shall expect to third and longest, M, is the repose lever. The last lever; another, L, unlocks the escape-wheel; and the 4,000ft. to 4,500ft. per week. The great ad- hear of its adoption throughout the building. The vantages of Mr. Jackson's system are safety, clean- boiler is of 4-horse power, and is nearly 3ft. in dia

*Horological Journal.

This

rests upon the detent N. This is a lever composed of a short and a long arm; and its fulcrum or arbor is hang on pivots beiween a cock and the frame. The short arm lies horizontally, and it is only 1-32nd part of an inch in length. The other arm, which is

L

D

left the pallet it falls a little farther, which brings the short arm L in contact with the arm V of the detent T and discharges the escape wheel. The next pin in the wheel instantly again raises the impulse lever before the return of the pendulum to be ready for the next impulse; the pendulum receiving an impulse only at each alternate vibration. The small weight on the long arm of the detent M is adjusted to keep the detent nearly equipoise with the repose arm when the latter is resting on it. It has only a small preponderance to prevent the repose arm when it drops on to the detent from forcing itself past it. The weighted arm of the detent rests on a bankingpin. This pin and the deer-foot piece jointly are only needed to preclude the possibility of "tripping." The pendulum, it will be readily understood, has in unlocking not the full weight of the impulse lever to oppose it, but only the preponderating weight of the detent long arm, which is not only really very inconsiderable, but, also, what is of more importance, perfectly invariable. The impulse lever, when it leaves the impulse pallet and brings the arm L against the lever V of the detent T and unlocks the escape wheel, overcomes the force of the train by a force plus that of the impulse, equal to the momentum it has acquired; and the resistance it has to overcome is Mless than the force which raised it in the ratio of the radial distance of the lifting pins and the locking teeth of the escape-wheel.

a little pendent, is three-quarters of an inch in length and it is partly screwed for the adjustment of a smal weight which it carries of two or three grains. At 6in. from the point of suspension, a discharging pallet, shaped somewhat like a ratchet catch, is pivoted into a cock which is screwed to the uppermost traverse bar of the pendulum. This pallet, O, lies horizontally, and is kept in this position by a banking pin on the cock. It is so placed that its front edge coincides with the vertical line of suspension, and it is adjusted backwards, or forwards,

N

by having the screws which fix the cock pass through slotted holes in the traverse bar. This adjustment, as will be shortly seen, corresponds to the turning of the lifting pallet of a chronometer to its proper position on the balance staff. At 17in. from the centre of suspension is a curved, light, traverse steel bar, into the centre of which a piece of agate, forming the impulse pallet P, is fixed. The depth of the pallet into contact with the impulse lever is adjusted by having the bar to slide up and down the pendulum rods. When at the proper position it is secured by screws. R is an intermediate lever of two arms each 5 in. in length. Its centre is lin. from the vertical line of suspension; and its upper arm is in the plane of vibration and slants towards the vertical line at which its point meets the lifting pallet O. The other arm is pendent and slightly curved at its end which rests against the side of a short flat pin standing upright from the centre of the detent lever N. On an arbor pivoted between the frames are two arms; the one, T, acts as a detent for the escape wheel, and the other, V, is the lever by which it is

unlocked.

The action of the escapement is as follows:-The escape-wheel moves from right to left, one of the pins in the side of the wheel raises the short arm D, and, in doing so, the impulse lever I is raised to a position ready for impulse, and kept there by the repose arm, M, being at the same time brought up and left to rest on the detent N (the repose arm has a small deer-foot piece at its extremity to allow it in being raised to pass the detent). The escape wheel passes farther round until the pin has left the lifting arm D, and now one of its locking teeth comes in contact with the detent T, which stops it. The pendulum in vibrating to the right discharges by the lifting pallet O and intermediate lever R the repose arm M off the detent, when immediately the impulse arm I impinges by gravity on the pendulum pallet P and gives the impulse. After the impulse arm has

It is to be observed that in this escapement exact divisions of the escape-wheel teeth and pins is not important in so far as any effect on the pendulum is concerned, and therefore any wear of the locking teeth and pins, or of the pivots of the several parts,

But apart from other objections which might be made to that escapement, the mode of unlocking substituted a greater for a less evil, and destroyed all that is distinctly important in a gravity escapement.

BEET SUGAR IN NEW SOUTH WALES. would seem that there are about 100 planters AROM the returns which have been gathered, it who have gained sufficient confidence in sugar to risk a portion of their land and labour in its production. The area under cultivation for this crop is stated by the "Grocer" to be 622 acres. A very large portion of this land is in small plots of one to eight roods, not planted to be crushed, but to afford cuttings for extensive planting when machinery should be introduced. Thus the majority of the growers on the Richmond and Hastings rivers have merely created cane nurseries, to save themselves from the necessity of buying cuttings at a high rate; they are in readiness for a great move, and are looking forward to the assistance which capital is about to give them. The absence of machinery is the only bar to energetic operations on their part. In some districts the difficulty has been met, as, for instance, in the Upper and Lower Clarence, by the formation of companies and the purchase of machinery. There is undoubtedly great advantage in this system of co-operation, because planting and the provision of machinery proceed simultaneously. This sugar growing occurs on the alluvial lands of the Manning, Richmond, Hastings, Clarence, Macleay, Paterson, Hunter, Myall, and other rivers, the plantations being from 10ft. to 500ft. above the level of the sea.

A

NEW METHOD OF BRICKMAKING.

VERY excellent and scientifically complete mode of brickmaking has just been established (says the "Aberdeen Free Press ") at Ruthrieston, by Messrs. Keith, Harrimann, and Watson, of the Northern Patent Brick Works. The new works are constructed on the principles of Hoffman and Licht's patent annular ovens, only that the kiln-if it may be so called-in place of being built in the form of a circle has been built in the form of an oval. Let the reader, then, imagine an oval 175ft. in length and about 95ft. wide, as the extreme width. The circumference is formed of something, like a small railway tunnel, arched with firebricks and strongly bottomed with the same. There runs round the whole oval the tunnel, as we have called it, being a chamber about 15ft. wide and 8ft. to 9ft. in height; the outer walls, 10ft. thick at the base, and in which are twelve openings or doors, dividing the whole into as many sectional chambers. Inside the tunnel is another brick wall, or rather double wall, filled with earth in the middle, with smoke chambers, and a number of flues pointing towards the centre of the oval, from which rises the chimney stalk, 175ft. high. In the tunnel we have described the bricks are burnt. As we have said, the tunnel is divided into twelve chambers. Each of these is capable of containing 15,000 bricks, representing a day's produce of the ovens. The modus operandi is this:-In place of only one apartment or chamber being filled at a time, the whole are filled, save one, which is being emptied of the burnt bricks, and another next to it, which is being simultaneously filled with "green" bricks, the fire being meanwhile kept up in only one chamber. But it is here that the special value of the patent oven is seen, for while the fire is led round from one chamber to another, feeding coal through a series of small metal-covered is not so injurious as it would be in other escapements. holes in the crown of the arch (the whole of the This escapement is no more liable to wear than any chambers being hermetically closed up to the one other; but, supposing the locking teeth should by that is being emptied, which is shut off at the end wear become blunted and shortened, or the pins even nearest the fire by an iron door), the hot air and half worn through, it is obvious that the impulse flame, finding no other means of escape, go forward would not in any way be effected. The repose arm into the chambers in advance of the fire, gradually would rise to a shorter distance above the detent be- heating up the wet bricks. Nor is this all, because fore falling back to rest on it, and the escape-wheel the cold air that comes in where bricks are being would unimportantly have a little farther drop to emptied must pass through a series of chambers in its detent after the pins had left the lifting arm. The which the bricks burnt on four or five days precedwear of the teeth would also give them a little less ing are cooling. It touches, first, a chamber of hold on the detent, which would be of no consequence, nearly cooled bricks; next, one burnt a day later, for the wheel is discharged by the falling of the im- which is considerably hotter; then another, hotter pulse lever after the latter has left the pendulum, still, till by the time it reaches the fire it is quite at and therefore the pendulum cannot be effected by any the point of combustion, carrying forward the flame change on the duration of the unlocking. The only in waving lines among the interstices of the burnt parts in which much wear could effect the impulse bricks. There is thus secured the utmost possible are the pivots and holes of the detent arbor and the economy of heat, and, at the same time, any smoke socket and pivot of the deer-foot piece. But the re-evolved is thoroughly consumed, the only visible pose arm M is about four times the length of the im- emanation" from the top of the chimney stalk being pulse arm, and therefore any wear in these parts a little steam off the green bricks when they begin could only advance the impulse arm upon the pendu-to feel the influence of the heat. The economy in lum pallet a very inappreciable distance, and this might fuel which is secured by these means is, of course, compensate the effect of any wear which might have taken place on the pendulum pallet and impulse lever. The pendulum of this escapement is completely detached beyond the angle of impulse; and the impulse is given at the centre of vibration, equally before and after zero. No oil is required except at the pivots. Mr. Webster, of Cornhill, described in a paper to the Society of Arts, three of four years ago, an escapement of his contrivance in which the impulse levers, and not the pendulum, unlocked the wheel-work.

[graphic]

obvious, while the scientific principles on which the power of the fire is concentrated enable the cheapest coal dross to be used in firing. All these arrangements will materially cheapen the price of bricks.

IT is stated that the project of uniting Lake Huron and Lake Ontario bids fair to be a reality. Able engineers have decided that the work is feasible, and that it will not cost more than forty million dollars.

MACHINERY

WEST

FOR TURNING CHILLED ROLLS

STOCKTON IRON COMPANY.

BY MESSRS. CLARIDGE, NORTH, AND COMPANY, PHOENIX FOUNDRY, BILSTON.

[graphic][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]
« EelmineJätka »