« EelmineJätka »
LONDON: FRIDAY, OCTOBER 30, 1868.
contact with it. What follows is so well the converter which I analyzed is obviously described by Professor Miller, of King's not such as to injure the quality. The
College, in a report now before us, that we steel iron was subjected to many severe MECHANICS' MAGAZINE.
prefer giving it in the Professor's own words. tests. It was bent and hammered sharply He says :-"In about two minutes a reaction round, without cracking. It was forged and commenced ; at first a moderate tity of subjected to a similar trial, both at a cherrybrown nitrous fumes escaped; these were red heat and at a clear yellow heat, without followed by copious blackish, then grey, then cracking ; it also welded satisfactorily.” The
whitish fumes, produced by the escape of Professor concludes his report by stating that HEATUN'S DIRECT STEEL PROCESS. steam, carrying with it, in suspension, a por- Heaton's process is based upon correct THE HE names of Parry, Uchatius, and Martin tion of the flux. After the lapse of five or chemical principles, and that the mode of
in earlier, and those of Bessemer and six minutes deflagration occurred, attended attaining the result is both simple and rapid. Siemens in more recent times, are insepa- with a roaring noise and a burst of a brilliant
Besides the report of Professor Miller, we rately connected with the history of steel yellow flame from the top of the chimney have before us reports from Mr. Robert making. Another successful worker in this This lasted for about a minute and a half, Mallet, C.E., and from Mr. David Kirkaldy, direction has lately come before public and then subsided as rapidly as it commenced. upon the general principles of the invention, notice-Mr. John Heaton, who has brought When all had became tranquil, the converter and the results of the testing of a number of to a successful issue a direct method of pro- was detached from the chimney, and its con- bars of Heaton's steel iron. Both of these ducing steel which bids fair to place other tents were emptied upon the iron pavement reports are exceedingly satisfactory, and bear processes in the shade. This process has of the foundry. These consisted of crude valuable practical testimony to the high chabeen at work for many months past in one steel and of slag. The crude steel was in a racter of the process and the material prolocality—the Langley Mill Works, in the pasty state, and the slag fluid; the cast iron duced. Mr. Mallet's conclusions Erewash Valley, near Nottingham-upon a perforated plate had become melted up and "1st. That Heaton's patent process of convermanufacturing scale, and with complete suc- incorporated with the charge of molten metal. sion by means of nitrate of soda is at all cess, both metallurgic and mercantile. It is, The slag had a glassy blebby appearance and points in perfect accord with metallurgic however, only just beginning to emerge from a black or dark green colour in mass.”
theory. That it can be conducted upon the the obscurity in which it has been so far kept,
The crude steel thus produced from great scale with perfect safety, uniformity, through circumstances, we believe, princi- Heaton's converter is broken up, and after and facility, and that it yields products of pally, if not wholly, financial. The Heaton the lumps have been squeezed under the very high commercial value. 2nd. That in process is a direct chemical reaction, and shingling hammer, are again heated in a point of manufacturing economy or cost, it consists in applying to the molten crude iron common balling furnace. They are after- can compete with advantage against every nascent oxygen developed at the moment of wards rolled or forged into bars or masses of other known process for the production of contact between the molten cast iron and any required form. In this condition the wrought iron and steel from pig iron. 3rd. such salts and nitrates as yield oxygen under material is called by the inventor - steel Amongst its strong points, however, apart those conditions. The idea of decarburizing iron," which, in fact, is a product obtained from and over and above any mere economy crude iron by the use of nitrates is, we believe, from the crude steel by taking out the carbon in the cost of production are these :-It to be found in many chemical works, and is in the re-heating furnace. It is an iron enables first-class wrought iron and excellent therefore no novelty.
But the fact of its which is nearly free from sulphur and phos- steel to be produced from coarse, low priced being carried out in practice to a successful phorus, possessing great strength and tough- brands of crude pig irons, rich in phosphorus issue is, and therefore reflects the highest ness, and is for structural purposes equal to and sulphur, from which no other known procredit on Mr. Heaton. The salt employed the renowned wrought iron produced at Low- cess, not even Bessemer's, enables steel of by Mr. Heaton is the nitrate of soda, which moor and Bowling Works. It welds perfectly; commercial value to be produced at all, nor is much more plentiful than nitre. It is not it is tough both hot and cold, neither red-wrought iron, except such as is more or less decomposed in presence of fluid cast iron with short nor cold-short, and forges beautifully either cold short' or red short.' Thus the same intense energy that nitre is, but at both the test temperatures for iron-a low wrought iron and cast steel of very high still would prove more or less unmanageable red, and a clear yellow heat. This steel iron qualities have been produced in my presence as an agent for the burning out of the silicon, is in itself a very valuable material, which from Cleveland and Northamptonshire pig carbon, sulphur, phosphorus, &c., were it has been produced ready for market without irons, rich in phosphorus and sulphur; and not for the extremely simple but beautifully the intermediate process of piling and balling. every ironmaster, I presume, knows that'firsteffective apparatus invented for its applica- From this material Mr. Heaton produces his class wrought iron has not previously been protion, and which constitutes, in fact, the cast steel in the following manner :-The duced from pig iron of either of those disessence of Mr. Heaton's patents, of which he cakes, after they have been squeezed by the tricts, nor marketable steel from them at all. has taken out several in connection with this shingling hammer, are broken up, put into Heaton's process presents, therefore, an almost process. This apparatus will be found illu- ordinary clay melting pots of the usual size, measureless future field in extending the strated at pages 350 and 351 of our present holding about Golb. each. To each 1001h. manufacture of high class wrought iron and issue, a detail description accompanying the of the material, about 2;lb. or 31b. of spiegel- of excellent steel into the Cleveland and other engravings.
eisen, or its equivalent of oxide of manganese great iron districts, as yet precluded from the The process by which the extraordinary and a little charcoal, are added, and the production of such materials by the inferior results we shall presently describe are pro- whole is fused and cast into ingots. It is nature of their raw products. It admits of duced is conducted as follows :-Cast iron of now excellent cast steel, and when the ingots the steel manufacture also being extended any quality is first melted in a common iron have been tilted in the usual manner, cast- into districts and countries where fuel is so foundry cupola with coke fuel. A known steel bars are produced fit for any uses to scarce and dear that it is otherwise imposquantity of the liquid iron-usually about a which steel is at present applied. Such is the sible.” ton—is tapped out into an ordinary crane Heaton process ; its simplicity and directness
Mr. Kirkcaldy's tests go to show that the ladle which is swung round to the side of the need neither comment nor praise at our
wrought iron made from Cleveland and converter. This latter is a tall cylinder of hands. boiler plate, open at the bottom, between
We have already referred to Professor resistance, bore a rupturing strain of 23 tons
Northampton pigs, and tested for tensile which and the floor a space is left. The con- Miller's report, which gives the following rein a conical covering, out of which an iron produced at the Langley Mills under his own The tilted cast steel made from the same verter has a firebrick lining, and terminates sults of analysis of three samples of metal per square inch, and an elongation of nearly funnel opens to the atmosphere. In the observation :
pig irons bore a tensile strain at rupture of bottom of the converter a number of short
above 42 tons per square inch, with an cylindrical pots, lined with brick and fire
elongation exceeding one-twelfth of the unit clay, are adjusted. Into the bottom of one
Pig (4). Steel (7). Iron (8).
of length. These results show the remarkof these pots a given weight of crude nitrate Carbon
able quality of the material, and the fitness of soda of commerce is put. The surface of Silicon, with a little tita
of the foriner for artillery, armour plates, and the powder is levelled and covered by a thick Sulphur..
boilers, and of the latter for rails, shipbuildcircular perforated plate of cast iron. One Phosphorus
ing, and all other structural uses. The iron of these pots thus prepared having been ad- Arsenic
and steel have also been subjected to the justed to the bottom of the cylinder, the con
treatment it would meet with in its manufacverter is now ready for use. At one side of Sodium
ture into girders and such like; it has also the cylinder is a bopper, covered by a loosely
been manufactured into tools, and the results, hinged flap of boiler plate. This plate is
in both cases, as stated in a report by Messrs. raised, and the ladle full of liquid cast iron
Allibon, Noyes, and Co., are as favourable to is poured into the converter, and descends “ It will be obvious from a comparison of the material in this as they are in other upon the top of the cold cast iron perforated these results," says the Professor, " that the respects. In short, nothing has been left plate. The plate does not float up nor be- reaction with the nitrate of soda has removed undone that could tend to have this importcome displaced, nor does any action become a large proportion of the carbon, silicon, and ant invention fairly and honestly tested, and, apparent for some minutes, while the plate phosphorus, as well as most of the sulphur. in the words of Mr. Mallet, “ Ileaton's process is rapidly acquiring heat from the fluid iron The quantity of phosphorus (0-298 per cent.) constitutes, both with respect to economy of above it, and the nitrate getting heated by I retained by the sample of crude steel from production and utilization of inferior pig
2.950 0.113 1.455 0.041 0-318
0.266 0-018 0-298 0-039 0-090 0.319 0-144 97.026
0-149 traces 0-292 0-024 0-088 0-310 traces 98.144
Iron (by difference)
iron, one of those metallurgic advances which of the Martini rifle burst so frequently at PHOTOGRAPHIC LENSES. leave their mark indelibly on great national the base as to occasion a great escape of gas, industries."
VOME few weeks ago we called attention and to bring the rapidity trials of that arm Som
in these columns to the fact that the to a premature close.
in the next place, in best English opticians charge about twice as
the sand trials, the Henry worked perfectly, much for photographic lenses as French optiTHE MILITARY ARM OF THE
and satisfied that test fully, whilst the Mar- cians of the highest eminence do for lenses of FUTURE.
tini was not tested by throwing sand upon the same quality. And the French opticians N
necessary to remind our readers that at munition. Then, again, if we take the work. the brass work in which lenses such as Darlot's the time it was decided that the Enfield ing of the breech mechanism, we find that are mounted is infinitely superior in workmuzzle-loading rifle should be converted into that of the Henry rifle worked admirably manship to the average of English mounts, a Snider breech-loader, it was understood throughout the exposure trials; whilst, after and is surpassed by no makers in this country, that this was only a temporary arrangement. the Martini had been exposed for the same as anybody may see by a very short examinaIt was, in fact, a sort of stop-gap to meet length of time, only one shot could be fired, tion. We attribute the large sums wasted the pressing demands of the time for a mili- as the extractor would not work. An exami- by English photographers in lenses partly to tary breech-loader; but it was arranged that nation of the parts showed that the escape the fact that they often value a lens in proan entirely new weapon should be sought for of gas, consequent on the bursting of the portion to what it costs them, and do not, and selected for the army. Then came an
cartridges, had fouled the breech-piece, which especially in the provinces, have many opinvitation from the War Department for in-had also become rusty, and its action clogged portunities of comparing the working qualiventors to send in their designs for competi
and impeded. Finally, with regard to the ties of the lenses of different makers. They tive trial. During the time specified by the commercial consideration of the question, the also are led into the waste because some of Government advertisement for receiving the sub-committee report that the facility of pro- the photographic periodicals praise most competing rifles, 104 specimens were lodged. duction and cost of manufacture, are equal highly the lenses of whichever of the large Out of this number, it was found that 37 only in both rifles, thus showing that there is no English opticians advertises most largely in complied with the terms of the advertisement, advantage in that respect.
their pages, and most religiously keep back and these being again weeded out, left nine as Beyond the sub-committee's report, we hear from their readers the fact that the best the final selection for the prize competition. nothing more of the Martini rifle. Not so, French lenses are only about half the price of These were the Albini and Braendlin rifle, however, of the Henry, which has been brought the best English, and carried away the first the Burton rifle (two patterns), the Fosbery prominently forward in the subsequent rifling prize from the best English opticians at the rifle, the Flenry rifle, the Joslyn rifle, the trials, and has still maintained its superiority. last exhibition at Paris. Peabody rifle, the Martini rifle, and the Rem- All the rifling trials have been made with The publication of these facts by us necesington rifle. Of these nine examples, the Henry breeches, fitted to the various barrels sarily brought forth comments in the photoarm which proved itself worthy of the prize which were being tested, and many thousands graphic papers, the chief assertion in reply under the stringent conditions of the adver- of cartridges have been fired by this me- being that lenses by the best French opticians tisement was the Henry rifle. After the con-chanism without the slightest accident. Not vary considerably in quality, so that it is a clusion of the prize competition, the 67 arms only has the Henry rifle passed through every matter of chance whether a purchaser gets a which had not complied with the terms of the ordeal to which it has been submitted with good one, though sometimes, it is admitted, advertisement, and were therefore ineligible the most complete success with regard to the he does get a first-class lens from them. The for the prize competition, and between 30 breech arrangement, but also as regards its lenses of all makers, English included, vary, and 40 other rifles which were received after rifling, competing successfully with the most but with the best opticians in either country, March 30, 1867, from all parts of Europe and approved systems of rifling in this country, not to a considerable extent. The assertions America, were examined upon their merits. including those of Whitworth, Westley published here attracted the attention of the They were gradually reduced in number, as Richards, Rigby, Lancaster, and Dixon, of Photographic Society of France, and the had been the previous batch of 37, and against Enfield. Besides all this, the Henry rifle allegations of our contemporaries about the all these-old and new comers—the Henry rifle has won for itself honours in the field, both bad quality of French lenses were published was tried and held its own, complying fully at home and abroad. At Wimbledon the in its journal. In reply, Mr. Fowler, the with the requirements of the War Office. superiority of the Henry rifle was established Paris correspondent of the " British Journal But notwithstanding this result and the de- by its gaining---not for the first time--the of Photography,” received the following letcision of the Committee, a recent article in Duke of Cambridge's prize of £50, and eleven ter from a maker of French lenses :the "Daily Telegraph,” which is apparently other prizes ; whilst at the recent Tir
We have just received the bulletin of the Photobased upon a paragraph in the “Army and National at Brussels it virtually drove all graphic Society for June, and find, on page 151, an Navy Gazette,” leads us to imagine it pos- its rivals off the field. The Martini rifle article on English and French photographic lenses, sible that after all the Henry rifle, as a whole, has done absolutely nothing hitherto to which proves once more how many photographers may not become the military arm of the future justify the attempt to transform it into a ing, almost specially as we do, photographie lenses of inasmuch as there is a possibility of the successful arm. One of these altered arms the English patterns, we believe that we are in a posi, Martini breech supplanting the Henry breech. has, we believe, just been completed at tion to speak with knowledge upon this subject, and It will doubtless occur to some of our readers Enfield to the order of the sub-committee. we assure you that the French, when they like, can that the Martini rifle did not come out with The system has, however, as yet undergone make as good lenses as the English, and much satisfactory results from the competition, no actual tests for rapidity, endurance, and cheaper, for we can furnish leuses which will rival whereas the Henry did, and by taking the all the other conditions requisite to secure here is the reason :-The French makers have a prize, and by its subsequent successes, is en- the efficiency of a service arm. This solitary great competition to contend against, and are obliged titled to be considered as the arm of the gun is now being subjected to a few days' to content themselves with small profits; manual future. But the answer to this is that trial, and should it emerge successfully from work is also, we believe, cheaper here thau with our rumour points to certain alterations which this slight ordeal, the rience thus gained neighbours, who do not content themselves with a have been carried out at Enfield in the Martini may-if rumour be true-probably be re- relatively speaking, compared with the French optibreech in accordance with suggestions made garded as outweighing results obtained from cians. by the sub-committee. Thus, should this trials of the Henry rifle extending over two Whatever the “ British Journal of Photography" breech be eventually adopted, the credit will years. Such a conclusion may appear pre- may say, there are certain persons who, from the innot be due to the man whose name it bears, posterous, but it is one at which it is by no fluence of celebrated names, are induced to becomo although he will reap the honours and reward. means impossible for the sub-committee to price than if they had made their purchases in
Regarding the question from a general arrive. It is asserted by the “Pall Mall France; but this is the same for all articles. It is easy point of view, it appears to us that such a Gazette” that the Martini is “an advanced for us to prove what we assert to anyone who will course is very much to be deprecated. It is type of breech-loader,” because, we presume, take the trouble to procure a certain number of Engobviously unfair that public money should be it dispenses with the side lock and hammer ; portrait lenses, because in them is the difficulty of applied, and our public establishments be but we seriously doubt this assumed supe- manufacture, those for views being easy to make). devoted, to the improvement of the rifle of riority, as years of use have shown the non- We will take the same number of our lepses, as one inventor-and he a foreigner-over liability of the present lock to get out of nearly as possible the same style and class. We those of other inventors, including that of order, and it cominends itself to the service will cover up the English names and our own, and a well-known British gunmaker who has from the fact of its affording tangible as well the lenses shall be tried by competent persons who devoted years of time and thousands of as ocular evidence to the soldier of the con- French ; and we shall be happy if the gentleman pounds to the improvement of our military dition of his rifle with respect to safety. In who wrote in an English journal that he generally small arms. But looking a little more closely short, the superiority of the Henry rifle has found five French lenses bad out of six, should into the matter, we fail to see the justice to been so fully proved, and is so apparent to make this trial. We shall be glad to render any Mr. Henry in pursuing such a policy; we all, that it will be a great injustice towards further information in our power. rather see a great injustice perpetrated, for the inventor if that arm does not become the The fact is, that an optically perfect lens, the relative merits of the two arms must be military arm of the future. Should the Mar- giving, like that of a telescope, intensely sharp taken into consideration. Turning to the tini, with the alterations suggested by the definition in one plane only, is bad in porofficial report, issued by the sub-committee sub-comunittee, be adopted, it will afford one traiture ; therefore, as diffusion of focus must in April last, we find, in the trials for rapidity, more example of the treatment inventors ex- be introduced to a certain extent, such great the Henry rifle averaging sixteen rounds per perience at the hands of the British Govern- nicety of manufacture is not necessary nor minute. On the other hand, the cartridges I ment.
desirable in photographic lenses. Optical
glass, which will not do for the object
-glasses of telescopes are polished by the human hand by friction against the skin, perhaps English opticians who charge high prices polish their photographic lenses in this way.
A The “Illustrated Photographer” says that when letters appear in a journal praising the
FIG.5 lenses of a particular maker, the editor is not
A responsible, nor can he be charged with puffing
FIG.2. the expensive goods of that maker. can say is that if we admitted letters constantly praising the engines of one particular manufacturer, the manufacturer would be infinitely obliged to us, and his friends would ply us with a steady supply of the letters. If all three photographic journals had letters praising the goods of the same maker, there might be something in the above assertion ; but how is it that one photographic journal
FIG. 3. gets nothing but letters praising the goods of
A one maker, whilst another journal never gets any, but is full of puffs about a second
3 manufacturer ? The Illustrated Photographer " says that when it was first started, a rumour was set afloat by its opponents to the effect that it was a new journal started to write up the lenses of a particular manufac
F turer. We freely admit that such rumour has
-L no truth in it, but the fact that it got afloat, as admitted, proves that a section of the photographic mind in London does not regard as
FIG. 4. impossible an alliance between journals and the
B manufacturers of dear lenses. In our stric A tures on one or more of the journals, scarcely any allusion was made to any particular periodical, and we left the cap to fit where it might.
There are photographers in London who hold the belief that the suppression of the publication of the fact, that the lenses of the contemporaries to ascribe the circumstance a=0. In the former case, the formula be
W very best French opticians are only about of all the letters and paragraphs praising one
but WIXL half the price of English lenses, is done on optician going to one journal, and all the comes S=
2 purpose by one or more of the photographic praises of a second optician going to another, journals, and that the statement, that the best to physiological causes. It would be interest- we find the maximum strain upon the web French lenses are worse than the best English ing if the Ethnological and Anthropological occurs at the last bar 4 of the girder, and is is not true. Probably, these omissions are Societies of London would examine the heads
W accidental, and it may also be accidental that of photographers before and after death, to equal to The minimum strain upon letters and paragraphs praising one maker see if they can discover what peculiar struc
2 sin, always go to and get into the columns of one ture of the brain induces a man not only to journal, while statements praising another value the lenses of one particular maker, but the web takes place when a=0, that is inan as the best maker of lenses, go as un- to send commendations of that manufacturer's at the central part of the web. The posierringly to another journal. Of course, the goods to one journal only, and never to its tion of the maximum and minimum strains editors cannot help this. Their best way out neighbour. There must be some cause, which upon the web are therefore the exact reverse of the difficulty is to publish several articles the editors cannot help, why large masses of of what they were in the former instance.
There is one more case to consider before we telling their readers all about the relative the public are not only so divided in opinion, prices of the best English and French lenses. but post their different opinions to different pass on to the subject of the continuous trial of lenses between the best manufacturers is that the readers of one of these journals most generally occurring in practice. Having Then they might recommend a competitive journals without intermixture. Therefore it girder of two spans, and that is when there of each nation, wherein the results are not to may think one optician the best in London, already ascertained the effect of the dead be decided by's opinions,” but by figures. In and the readers of another journal may have load, we may omit it in our calculation of truth, an establishment for testing portrait the idea instilled into them that a second that of the moving load, as it would only lenses for a moderate fee, and stating the maker is the best, whilst we assert that a
complicate the investigation. At the same results in figures, is much wanted in London, third is as good as either, and his lenses time, in designing a girder, the two must be and then photographers could not be in- about half the price. Why not " write up
taken together, and their united strains profluenced by advertising puffs, or unreliable a competitive examination of lenses to unravel vided for, by simply adding the one to the opinions, but could learn facts for them- the discrepancy, the results to be stated in other. The strain upon the flanges is clearly selves. Moreover, the best optician would figures, not in “ opinions”?
a maximum when the rolling load covers the then soon be known, and get his reward in all
whole of the girder, and the amount may be justice.
EFFECT OF THE POSITION OF determined and the position by the formulæ Till we have some such establishment, or till the question at issue is unmistakably
THE LOAD UPON CONTINUOUS already given, bearing in mind to substitute decided, we recommend photographers who
the proper value for W. A little reflection
is necessary in order to arrive at an accurate want several of the very best portrait lenses T will be perceived, from what was idea of the manner in which the diagonal holiday. Then go to Paris and buy them of there exists an identity of position with It must be kept in view that the total strain the man who carried off the first prize at the respect to the maximum and minimum upon any one bar of the web is the difference Paris Exhibition, or of some other first-class strain upon the flanges in both these in- of the tensile and compressive strains brought Parisian optician. The purchaser will then stances, yet this similarity does not extend to upon it, and, accordingly as one or the other come home with as good lenses as he can get the web. To first determine the strain predominate, so is the nature of the strain to in England, and the saving in cost will clear generally, let W' equal the weight per foot which the bar is subjected determined. Let off a large part, if not the whole, of the run, and suppose the strain upon the bar 1 is us take the bar 3, situated between the centre expenses of his holiday in Paris. Why does required, then putting a for the distance of of the girder and the abutment A in fig. 2. not a good French maker start an agency in the bar 1 from the centre, we have S This bar is subjected to a tensile strain from London and challenge competitive examina- Wixa
L that portion of the weight lying between it tion of his goods?
The limits of a are a = –, and and the centre of the girder, and to a strain We recommend some of our photographic sin. 9
of compression, from the portion situated
between it and the abutment A, the actual vertical reaction the remaining halves. In DORSETT'S PETROLEUM FURNACE. strain being the difference of the two. Let order to arrive at the action of the strains, let the bar 3 divide the span into segments m and n, and supposing the movable load to B F. It is evident that the half weight of the and 500 tons burden, fitted with Mr. E.
us first direct attention to the cantilever part ANOTHER trip was made on Friday last, have advanced only over the length of the segment F A may be considered in the light Dorsett's petroleum furnace, in which the segment n, it is clear that the compressive of a weight suspended at the end of BF, strains which would come upon the bar 3, if as represented in fig. 5. From this it is gas of the creosote is burned. The results the load covered the whole of the girder, do apparent that as the flanges of a girder than on the previous trip, recorded in our
on the present occasion were more favourable not exist. Consequently, the maximum strain can only support strains of a horizontal upon the bar 3 is produced when the rolling nature, there is no strain upon them at the issue for the 16th instant. This was in conload covers the longer segment into which it free end of the cantilever, or at the points been improved upon, which enabled the endivides the total span of the girder. As a F, of contrary flexure in fig. 3 and 4. The upon any diagonal bar in the web of a girder a maximum at the abutment A, that is at B steam. On the present occasion, Mr. Dorsett general rule, therefore, the maximum strain strains upon the flanges in fig. 5 will be gines of the “ Retriever” to attain a speed of subjected to a rolling load is produced when in figs. 3 and 4, and the strains that load covers the longer segment. Instead will be uniform upon all the diagonals 1 and 2 placed the matter in the hands of Mr. of the bars at the centre being under no when only the weight at the end is considered; and Mr. Anderson, from John Penn and Sons. strain, which it has been shown occurs when but a maximum upon bars 4 when the weight These gentlemen kindly consented to take the load is fixed, and placed at the centre, upon the cantilever itself is taken into account. they are acted upon by a maximum strain Having disposed of the cantilever part of this notes, and to report upon the consumption of when the rolling load covers the half of the compound principle, let us now ascertain how fuel, and the work done, &c. Their report span. Similarly, the maximum strain upon the other segments are affected by the same
has not yet been issued, but we hope to place the end bar is produced when the whole span condition of loading. A very little reflection it before our readers next week. In the is covered, which accords with the same con- will point out that the segment 4 F is simply the trip were highly satisfactory, and proved ditions as those of a fixed central load. If a horizontal girder supported at the points A W I be the rolling load, the maximum strain and F, and, consequently, the amount of the that with the mechanical arrangements perWI
strains and their position may be determined fected, we may expect the Dorsett method of at the end bars is x cosec. 0, and at the from the cases already investigated. The burning liquid fuel to become the adopted
points F F of contrary flexure will be situated system.
under the conditions just described, at a discentre The strains upon the diagonal tance from B equal to three-quarters of the
THE ABYSSINIAN TUBE WELL. span. It must be borne in mind that at the bars of the web are, therefore, under a points of contrary flexure the character of the Tsuch notoriety, from its usefulness and uniform load, a minimum at the centre, and strains in the flanges changes, the compressive a maximum at the same point with a rolling becoming tensile, and vice versa.
efficiency in Abyssinia, is now so well known load covering half the girder. These points Since the inanner in which continuous gir- to the public that a description is here hardly of difference should be carefully noted, as ders are affected by straips depends altogether necessary. Should, however, there be any they not only serve to afford correct ideas upon upon the position of the points of contrary who are unacquainted with its construction, the effect of the position of weights upon a flexure, as they determine the relative spans they will find engravings and descriptions in girder, but they act as an immediate check of the cantilever and the independent girder, the MECHANICS' MAGAZINE for March 20 upon an erroneous calculation.
the first step is clearly to find the position of last, page 216. In the present instance, Having now investigated the case of a those points themselves. Practically, as we therefore, we need only refer to some very girder of a single span and its loading, we have before mentioned, the problem resolves successful experiments, which were carried may now proceed to treat of continuous itself into ascertaining the limits of the varia out at Plaistow, on Saturday last, and which girders, and will commence with the simplest tion of the points. Instead of the load being were repeated on Wednesday, by Mr. Norton, instance, where it consists of but two equal uniformly distributed over both spans, let it of Belle Sauvage-yard, Ludgate-hill. The spans, as represented in fig. 3. We shall cover one only, from C to B (see figs. 3 and 4). experiments consisted in driving a number neglect, in future, the consideration of a The'deficction of the span B C will, therefore, of tube wells of various diameters, the results weight at the centre, as it possesses but little be increased, since the counteracting influence beinganinvariable success. A 2-inch diameter practical interest, and shall include the cases of the load upon the span B A is removed, tube well was driven down to water, the pump only of a uniformly distributed and a vari- and the point F to the right of the pier B screwed on, and at work in fifty minutes. able load. The distinguishing characteristic will be shifted nearer to it to F), and the A 14-inch well—the Abyssinian size-was of all continuous girders is that their curve other point F to the left, farther from it. driven down, and water pumped in twenty of deflection is not uniform, but assumes a The cantilever portion of the girder will be minutes. There were also trials of the wellwave-like contour, shown in fig. 4, and the of a maximum length when the load is uni- known Californian pump, which has been determination of the points where the curve formly distributed over both spans, and if the adopted as a portable fire engine worked by changes from concave to convex, and from strains be calculated in accordance with this hand. This machine delivered at the rate of convex to concave, is the problem to be assumed length, they cannot be increased by 600 gallons per hour in a consecutive stream. solved. These points are represented in any other position of the load. At the same But the most interesting part of the trials figs. 3 and 4 at F, and are usually termed the time that the distance B F is diminished was that which related to a recent improvepoints of contrary flexure. They can be to B F1, that of C F beccmes increased to ment of Mr. Norton's upon the present pump fixed with perfect accuracy when only a load CF, and therefore the span of the indepen- used by him, and by which means he can uniformly distributed has to be dealt with, dent horizontal girder undergoes an augmen- obtain water from any depth. In ordinary, but the question becomes exceedingly com- tation. Instead of being, as under the former the pump is screwed on to the top of the plicated when the load is of a variable cha
3 x L
tube; by the new arrangement, however, the Tacter, and, in fact, it is impossible to deter- conditions, equal to it has a new value tube is made to form the working barrel, the mine it for every position of the weight, and
bucket being fitted within it. By this means, all that can be done is to assume certain which must be ascertained. Putting S to water can be got at even at a depth of 60ft., limits between which it may practically be equal the maximum span of the independent as was successfully demonstrated by the reconsidered to vary. An accurate knowledge segment CF! W the weight of the un- cent experiments. of the relations existing between the strains loaded span, and W' that of the loaded, induced upon the various portions of a con
0.125 W tinuous girder is essential towards compre
GREEN'S PATENT STEAJI BOILER. hending the advantages of the principle, and
WI the points also in which its theory is not fully The extreme positions of the points of con THE
HE accompanying engraving illustrates an borne out in practice. The girder represented trary flexure being fixed, the calculations are by Messrs. E. Green and Son, of the Phænis
advanced type of boiler which is manufactured in figs. 3 and 4 may be regarded as composed carried on precisely in the same manner as Works, Wakefield, and who are the patentees. of two distinct systems, the one embracing the previously explained, and the maximum The boiler is made either with wrought-iron, castcantilever and the other the horizontal girder. strains both in the fanges and web will occur iron, or steel tubes, and its advantages are security If we were to suppose the structure to be at the same points, allowing simply for the from violent explosion, large heating surface, and severed at the points of contrary flexure F F, difference between the latter and former span facility of cleaning. The surfaces which become we should have the following result:--The of the end segments. If S be the span of the coated with soot are easily cleaned in the same double cantilever portion F B, B F would sus- independent girder, and S1 that of the adjoin- way as are the patent fuel economiser pipes made tain itself, while the two separate end parts ing cantilever, then when the load is uni- by the same firm. Thoso boilers are very portable, A F and C F would fall down. This at once formly distributed, S + S1= L. But when being built up in single rows of pipes. No bolts indicates the relative duties they perform and the load only covers one span, the assumed are used in making the joints, and no flat or flange the proportions of the load they mutually lengths of the two portions of the girder in joints are exposed to tho flame or heat. The cost
of these boilers is less than an ordinary two-flued sustain. It is clear that each cantilever BF calculation have not this value. In other Cornish boilor, while its safety is far greater. In sustains its own share of the load, and in addi- words, S + S!> L. The next simplest case
our engraving, fig. 1 is a transverse and tig. 2 a tion half that of the adjoining segments FA presenting itself is that of a continuous girder longitudinal section of one of these boilers, tig. 3 and FC, the abutments supporting by their | of three spans.
being a sectional plan. It has 2,300 square feet of
heating surface and 35 square feet of grato surface, and is of 80-horse power nominal. Three of Messrs. Green's boilers are working at a cotton mill of 60,000 spindles with 750-horse power. The boilers have been in operation five or six years, and are in use to the extent of several thousand horse power. In the earlier boilers some difficulties were encountered, but time and experience have enabled Messrs. Green to overcome these, and there is little doabt that this class of boiler will supersede the large wrought-iron boilers which are constantly exploding with such fatal results.
TUE number of visitors to the Patent Office Museura, South Kensington, for the week ending October 24, was 3,486. Total cumber since the opening of the Museum, free daily (May 12, 1858), 1,418,884.