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in this country, it is, we understand, Water Works the rate of filtration with about to be employed by Messrs. Easton the ordinary filter beds varies from about and Anderson for the filters at the Ant- 1} gallons per square foot per hour in the werp Water Works, which they are now case of the East London and the West in course of construction. To determine Middlesex Works to as much as 4 gallons the suitability of the spongy iron for ef- in the case of the Lambeth Works, but fectually dealing with the Nethe water the average rate for all the works is dewhich is to be used for the supply of cidedly under 2 gallons per square foot Antwerp, Messrs. Easton and Anderson per hour, so that the results which have recently carried out a series of ex. Vessrs. Easton and Anderson have obperiments on a considerable scale, and tained with spongy iron, and with a water these have yielded results of much inter- greatly in need of filtration, point to the est. The arrangement employed con- possibility of employing filter beds very sisted of two cast-iron tanks, each hav- materially smaller than those ordinarily ing a horizontal area of 342 square feet, necessary. while the one was about 11 ft. and the So far as experience at present goes, other 75 ft. in depth. In the larger tank the spongy iron in filters requires no rethere was placed on a suitably construct- newal. Its action appears to be to proed brick bottom, a depth of 3 ft. of duce an oxidation of the organic matters spongy iron and gravel mixed in the pro- in the waters traversing it, the result beportion of 1 to 3, while above this was ing a discharge from time to time of placed a bed of Harwich sand 18 in. in carbonic-dioxide. We have referred to thickness. From the bottom of this fil- the testimony of the Registrar General tering tank, the water was drawn off to to the effect of spongy iron, and we canthe second tank, this latter containing, not do better than quote from his report as filtering material, a bed of gravel for 1877 the following paragraph reabout a foot thick with 2 ft. of Harwich specting it. He says: “The Thames sand above.

was in high flood during nearly the The object of the second filter is as whole of December, and its water was follows: In passing through the spongy loaded with organic impurities of the iron a small quantity of iron is dissolved most disgusting origin. It may be inin the form of protoxide, and if not re- teresting to those who can afford the cost moved it would, when converted into of domestic filters, to know that even this peroxide by the contact of the water with polluted water can be chemically purified the air, be thrown down in the form of by filtration through spongy iron. I have a brownish deposit. In the spongy iron inserted in the analytical table, for the filters for domestic use the further oxida- purpose of comparison, the results yieldtion of the protoxide is effected by an ed by the Grand Junction Company's admixture of manganese binoxide, the water, after passing through a spongy peroxide of iron being thus formed and iron filter, which had been in use for retained in the filtering material. This more than a year. The filter removed use of the manganese binoxide would not nearly nine-tenths of the organic matter, be convenient on a large scale, and in the and more than one-half of the hardness arrangement we are describing the water from the water.” The table here referred after passing through the spongy iron in to is annexed, the quantities being given the first tank is allowed to come in con- in parts per 100,000. tact with the air in the second tank, when The manufacture of spongy iron on a the peroxide of iron is thrown down and large scale is an interesting process, and arrested by the filtering material which we may hereafter have something to say that tank contains, thus allowing the concerning it. Meanwhile, however, we water to be delivered perfectly clear. may state that Mr. Bischof has taken

With the arrangement we have de- Dr. Siemens' well-known experimental scribed, Messrs. Easton and Anderson works at Towcaster, and is making found that they could efficiently filter spongy iron there in the Siemens revolvthe Nethe water at the rate of 150 gal- ing furnace, which has proved admirably lons per square foot of filtering surface adapted for the purpose. Considering per 24 hours, or 64 gallons per square the results which have been gained with foot per hour. At the Metropolitan | domestic filters, and the promising data

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afforded by Messrs. Easton and Ander- | be watched with much interest, and we son's experiments at Antwerp, the appli- hope in due time to be able to place full cation of the system of spongy iron fil. information regarding the results before tration at the Antwerp Water Works will lour readers.

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WEIGHT IN LOCOMOTIVE CONSTRUCTION.

From “ The Engineer.” THE “Links in the History of the and we have no reason whatever to think Locomotive,” which we publish from that finality has been reached in this time to time as we succeed in picking direction. Locomotives are not made them up, even if worked into a continu- heavier for the sake of securing adhesion ous chain, extending from 1829 to 1880, alone, but in order to secure immunity would be complete only for a day or a from breaking down. In other words, month. At the end of some such period they are made much stronger than they a new type of engine would be built, and used to be. Thin boilers, and frame a new link would have to be added to plates seven-eighths of an inch thick, the chain. Put in another way it may be have given place to 15 in. plates ; cylstated that locomotive engine construc- inder castings are heavier, motion bars tion is a thing of continual progress. have increased dimensions, pins are made It is difficult, indeed, to find any branch larger. In short, engines are made of mechanical engineering in which stronger all over than they were made a changes in design, and form, and few years ago, and for the same reason proportion, so rapidly succeed each they have risen from a maximum weight other. There is not a railway in the king of 30 tons or thereabouts to a maximum dom which is now worked by engines of of 36 tons, or even more. We speak now precisely the same pattern as those in of tender engines. In tank engines the favor ten or even five years ago, and it change is still more marked; up to about is to be assumed that novel types are fifteen years ago a tank engine wbich adopted not simply for the sake of weighed more than 30 tons was an exchange, but because some advantages ception. At the present moment there are supposed to be gained. A glance at are bogie tank engines working the Tilthe direction which progress in locomo- bury and Southend Railway which we tive construction is taking may not be understand weigh 56 tons in running found uninteresting.

order. Mr. Kirtley's Crystal Palace The most prominent feature in the tank engines weigh about 50 tons in modern British locomotive of the most working order, and various other examimproved type is its great weight. ples of heavy engines could be cited. English and Scotch locomotive superin- We may be excused, perhaps, if we tendents have gone on year by year digress here for a moment, to say that making their engines heavier and heavier, l it is by no means easy either to escertain

the weight of an engine in working drivers, perhaps, but the hauling power order or the distribution of weight on of both will be practically the same, and the wheels. Locomotive superintendents in the long run it will, we venture to do not always possess the means of think, be found that the light engine will weighing their engines as a whole, and not require more repairs than the heavier they even less often can weigh them engine. It may seem a hard thing to wheel by wheel. For this reason rather say—and we say it with some reluctvague statements get into circulation, ance-that the modern designers of locosome of which are not quite true, while motives do not manifest as much ingeothers may be true. We recently heard nuity of skill in scheming as those who it asserted, for example, that sft. driving Lave gone before them. The locomotive wheels of the single outside cylinder superintendents of to-day have an enorengines of the Great Northern Railway mous stock of accumulated knowledge carry 19 tons or a little over now, or to draw upon, which was not possessed about four tons more than they did at by the men of the last generation, and first, as they were found to lack adhe- they have, besides, tools and materials of sion. The extra weight has been ob- the highest perfection, and there are tained, of course, by a readjustment of comparatively few demands made on the springs. Whatever uncertainty may their inventive powers. The best feaexist as to precise weights, there can, tures in the modern locomotive are its however, be no doubt that, as we have simplicity and its workmanship. The said, weight has, on the whole, aug. display of a little more originality would, mented and is augmenting. Not a few we have no doubt, materially improve experienced locomotive superintendents the engine. The essence of success lies hold that we are in this respect pro- in putting weight into the right place, gressing in the wrong direction, and that and in so disposing our materials that engines are now made heavier than they they may be loaded and worked to the need be made, and that just as good re- best advantage. In this way a great sults could be obtained from lighter deal of weight may be saved. Let us machines. The question ought to admit cite as an example of what we mean, the of being readily settled. The modern staying of fire-box crowns. The bridge engine is in many cases called upon to do stays for a fire box will weigh with studs, more work and harder work than its nuts, etc., 15 cwt. or 16 cwt.

We have predecessors. This may be granted, heard of cases in which they weighed 30 but it is by no means clear that it must cwt. The weight of vertical sling stays, be made heavier to enable it to do this doing the same work much better, would additional duty. The adoption of steel not exceed 5 cwt. or 6 cwt. rails opened up new possibilities to the It should by this time be well known locomotive designer, and he has not been that engines have to go into the shops slow to avail himself of his chances ; but for repairs to wearing surfaces more frewe may ask, what has really been gained quently than for any other cause. Axle in this way? Locomotive improvement brasses and axles are a fruitful source means less first cost or less cost for of trouble, and it is much to be regretted repairs, or less cost for fuel or more haul that all railway lines are not laid for a ing power. Is it certain that increased gauge of 5 ft. This would have given weight will entail any one of the advant- 34 inches more space for bearings. Four ages we have named? We think not. bearings would have been improved, One man builds an engine with 17in. cyl- namely, the two crank pins and the two inders, 24in. stroke, and 1100ft. of heat- crank shaft journals. The two first ing surface, which weighs 28 tons; another could have each been made about 41 man builds an engine with the same inches long instead of 31 inches, and the stroke and cylinder and heating surface, 'latter could have been about 8 inches, or and it weighs 34 tons. Does it follow even a little more, instead of 7 inches. that the last must be the best engine of To get increased surface in these bearthe two? We doubt it. The difference ings should be the great aim of the between them will probably be very ! engineers' life; if he can succeed he will small. They will both be four-coupled, keep his engines out of the sheds.

Mr. one will have 6ft. and the other 6ft. 6in. Webb is apparently more fully impressed

with the importance of this truth than The augmentation in the weight of the any other engineer in Great Britain, and modern British locomotive with which it is for this reason that Joy's valve gear we have been dealing is due in same promises to prove so valuable. There is measure to the extended adoption of the much about Mr. Webb's practice of bogie. It was originally invented in this which we cannot approve, and he is con- country, and went thence to the United tent with a want of finish and style in States. Here the earlier lines—like the his work which is not paralled on any Manchester and Liverpool, the London great railway in Great Britain; but we and Birmingham, and the Great Western willingly concede that he does not waste -were nearly level and very straight. metal, and that he knows as well as any On such roads the bogie was a superman living just what to put in a locomo- fluity, augmenting weight and doing no tive, and no engineer better understands good ; but in the United States matters what are the causes which send locomo- were different. Their roads were bad, tives into the shops, and how best to steep, and crooked ; rigid engines could deal with those causes. There is we not traverse them, and speeds were slow, fear a tendency among too many design so bogies carried the leading ends of the ers of locomotive engines to produce engines and balance beams the trailing something which shall be grand and im- ends. In process of time we began to posing, and this is accompanied by a make crooked and hilly roads, and it was certain degree of carlessness concerning found advisable to adopt the bogie, which the effect which an engine may produce is rapidly growing in favor in this on permanent way. Nor is there quite country. It is now in use on the Midso much solicitude to keep down repair land, the North British, the Lancashire expenses as desirable. When everything and Yorkshire, the Great Northern, the has been made very big and very strong, North-Eastern, the London, Chatham, and very heavy, the designer fancies he and Dover, the London and Brighton, has done all that is needed; and if his and many other important railways in engines make but 12,000 or 14,000 miles Great Britain. Equalizing beams are in the year he does not take himself to not so much in favor. It is not easy to task; and yet had a little more care been say why. Mr. D. K. Clark's dictum taken to make the proper things big and that they make an engine unsteady did nothing else, weight might have been much at one time to stop their adoption, kept down, first cost reduced, and the and they have not since increased in fastaying powers of the engine greatly in- vor. They are, however, in use on several creased. We hear every now and then lines. The London, Chatham, and Dover of engines which have made their 90,000 and the Metropolitan Railways may be miles or so without going into the shops cited as examples. The bogie is no doubt for repairs. We heard only a few days of value in saving permanent way, since of an engine which had made because it consolidates it and brings it 251,000 miles. If we examine them we to its bearings before the heavily loaded shall find that the secret of their success wheels reach any given spot ; but the lies in large bearing surfaces, efficient bogie is by no means free from defects. lubrication, and the disposition of metal It adds a good deal, as we have said, to in the proper place. We are writing the weight of a locomotive, and yet more now not for the experienced locomotive to its first cost. It is a noteworthy cirsuperintendent, who fully recognize the cumstance, that as our railways departed truth of what we are saying, and for from the original perfection given to whom indeed we speak, but for younger them by such men as Brunel and Stephand less experienced men, and these can- enson, and we have adopted the bogie, not too strongly impress on their minds so in the United States, since track has the truth that weight as weight is as a been improved there a tendency has rule objectionable in a locomotive; and grown up to abandon the bogie and adopt that it cannot be made to compensate the English system. The change has for want of care and skill in proportioning begin with cars. Experiments have the various parts of the whole machine been made which show that the resistance to the discharge of the special duties to of bogies with a very short wheel base is be porformed by each.

much greater than that of bogies with

the axles far apart ; and four-wheeled generally found that a four-coupled engoods wagons of the English type are gine which weighs more than 30 tons is now being tried on American lines, and very severe on the road, unless it has a we have very little doubt that locomo- bogie; nominally 30 tons means 5 tons a tives without bogies will soon be built. wheel, not too much for a steel rail; really Some of the Pullman cars are carried by it means 7 tons or even 8 tons per wheel bogies with six wheels in each, and a on one pair of wheels, which is too much. wheel base of about 15ft., and it is obvi- In practice it will not be found, we reous that if these can get round the peat, practicable to make a four-coupled curves met with a locomotive properly engine too light, but it will be very easy designed and without any bogie can have to make it too heavy by putting metal no difficulty. It is also noteworthy that where it is not wanted. Every engine is American engineers are following Eng- too heavy which possesses more weight lish pracrice in another respect, and are than just enough to enable it to perform building locomotives with one pair of its work with efficiency. Drivers, we driving wheels only-a thing hitherto know, like heavy engines, because they unheard of in the United States. do not slip in bad weather; but a few

We have said that weight is objection- pounds of sand will as a rule do the work able in locomotives, and we feel that it is of some tons of iron, and much better, necessary before concluding to explain and locomotive superintendents should precisely what we mean, for so far as ad- not permit themselves to be too much hesion is concerned a locomotive cannot guided by the utterances of their men. weigh too much, and the heavier it is the The American engineers first taught us better. But the locomotive and the per- the real value of sand, and Mr. Adams, manent way ought always to be regarded when on the North London Railway, as parts of a whole; just as much one showed us how to use it. A little conwith each other as the table of a plan- sideration should be shown for permanent ing machine and the V grooves which way. Working expenses have of late carry it. As regards the rails, the lighter been increasing on all our railways, and an engine can be made the better. Now, it is worth considering whether some of if the locomotive superintendent did all this augmentation may not be due to the in his power to keep down weight, he growing use of heavier and heavier encould not get rid of it so far as to re- gines. It may be that the demands of duce the efficiency of a four-coupled en- traffic are so importunate that they cangine. He might, it is true, diminish the not be dispensed with, yet the running bauling powers of a single engine; but as of 20 or 25 ton locomotives over 75 16. these have or ought to have in all cases steel rails presents a tempting picture. large driving wheels, their power of pull- Such a road under such engines, once ing is never very great. Of the five or made, ought to last almost for ever; we six tons unnecessary weight now and cannot have 20 ton engines, but the nearer then put into an engine, only a portion we can keep to that weight the better reaches the driving wheels, and it will be for the road and the shareholders.

BRICKS AND THEIR HISTORICAL INTEREST.

From “The Builder."

In the autiquity of the brick as a build- strument in the hands of the builder ing material it is needless, nor is it indeed That throughout Asia Minor they were our intention, to insist. The great na- largely employed we have seen, only very tional collections of Europe, the British recently, proved in these columns ; M. Museum foremost in the number, show Rayet, in his work on Miletus, having us bricks, sun dried and baked, from the shown that the far-famed palace of ruins of Nineveh, and from the days of Cræsus was built of no more costly mathat city to the present moment bricks terials than honest bricks. What those have never ceased to be an important in- | bricks were, and their quality, are even

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