1845.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



155 



the same methods have been adopted as on former occasions; and in the 

 annexed table, such weights, deflexions, and numbers, have been selected, as 

 give a clear and succinct account of the methods adopted in the experiment i. 

 To each exiieriment, and to each iron, is appended a tabular form of results, 

 with the values, reduced to those of bars exactly 1 inch square ; the reduc- 

 tion being made, by supposing, — as is generally admitted, — that the strength 

 of rectangular beams is as the breadth, multiplied by the square of the depth, 

 the length being given, and that the ultimate deflexion is inversely as the 

 depth. The power of resisting impact, in each iron, is reckoned by the pro- 

 duct of the breaking weight, imdtiplied by the ultimate deflexion, and that, 

 upon the supposition, tliat the elasticity remains unimpaired, and that tlie 

 blow, in all cases, when the results are to be compared together, is given 

 with the same striking body, upon beams, all of which are of equal wciglit. 

 These suppositions, however, are not strictly true ; but the bars being all of 

 equal weight, tlie product above-mentioned, will give a comparative measure, 

 sulliciently near for practical purposes. The modulus of elasticity, which 

 may he taken as the measure of the stifl'ness of the iron, is given in pounds 

 for a base of 1 inch square, and is calculated, from the deflexion caused by 

 112 lb. on bars of 4 feet 6 inches between the supports.f 



Rl-IK. 



To lind, from the above Table, the breaking weight in recfangiilnr bars, 

 generally calling b and d the breadth and depth, in inches, and / the distance 

 between the supports, in feet, and putting 4'5 for 4 feet ti inches, wc have 



^= breaking weight in lb., the value of S being taken from the 



Table above. 



For example : What weight would be necessary, to break a bar of Low 

 Moor Iron, 2 inches broad, '.i inches deep, and G feet between the supports ? 



According to the rule given above, ne have i = 2 inches, d=.i inches, 1= 

 6 feet, and ^' equal 427, from the table. 

 4-5 xbd^ S 4-5x2x3- X 472 



Then -. = tt = G372 lb., the breaking weight. 



At the conclusion of the experiments on the British irons, as recorded in 

 the " Manchester Memoirs," a compendium of the whole experiments (from 

 which the preceding table is abridged), was calculated and brought at once 

 under the observation of the reader. This compcndinm exhibited at one 

 view, the results of each class of experiments, and being printed on a sepa- 

 rate sheet, was found useful in the workshops of engineers, millwrights, and 

 iron-founders, in determining the peculiar properties of irons, to which they 

 might have occasion to refer. It is further useful, for the purpose of regu- 

 lating the strength, flexure, and ductility of the different kinds of castings; 

 and a single glance at the table, will enable the practised iron-founder to de- 

 termine, with some degree of certainty, what sorts of iron to choose, in order 

 to meet the various objects of his trade. After the numerous experiments 

 made at diflTerent times, by writers on the strength of materials, and particu- 

 larly those conducted more recently, on iron obtained by the hot and cold 

 blast processes, it will be unnecessary, in this place, to extend the subject 

 baj'ond a record of facts as obtained in the foregoing results. Much may, 

 however, yet he done, not only in ascertaining, by a series of well-eonducted 

 experiments, the strength, deflexion, and elasticity of the different mixtures, 

 but there appears a still more extensive field open for research, into the che- 

 inietry and mechanism of the process of the reduction and manufacture of 

 the ores, which is probably of greater value than any other of the staple ma- 

 nufactures of this country. Considerable advances have already been made 

 in these inquiries, and more particularly as recorded in the works of Mr. 

 Mushet,* whose whole life presents an unvaried scene of experimental re- 

 search. 



Re.marks. 



Mr. Braithwaite eulogised the usefid result of the labours of Mr. Clay, 

 Mr. Ilodgkinson, and Mr. Fairbairn, which had been so well recorded by the 

 latter gentleman. It would be interesting to have, at a future period, an 

 account of the practical manufacture of iron, on the large scale, from the 

 Turkish ore, and he hoped that the cost of production would be given ; for 

 he conceived, that the great changes which had occurred in the processes of 

 manufacture, must be, in part, the cause of the present considerable reduc- 

 tion in the price of iron, particularly in Scotland, where the influence of the 

 use of the Blackband mine, and of the hot blast, was acknowledged. — It was 

 stated, that by Mr. Clay's process, as good malleable iron could be produced 

 direct from the hematite ore, by two processes, as by the usual five pro- 

 cesses with argillaceous ores. The question therefore, resolved itself into a 

 statement of the relative expense of the two methods of manufacture, and 

 both in a scientific and commercial point of view, it was of great importance 

 that clear information should be obtained. 



Mr. VitiNOLES agreed as to the importance of the cost of production being 

 known, but thought that it must be sought for from the manufacturers. 

 The attention of Mr. Fairbairn and Mr. Ilodgkinson, bad been directed to 

 the qualities of the various irons produced, and the restdls of their experi- 

 ments were of great practical utility. 



Mr. Phillips said, that be had analyzed several kinds of Turkish ore, and 



1 vide "Memoir! of the Manctlestcr Lit. and Phi]. Society," vol. vl (new series) 

 p»ge 273. ■ ' 



• " P«peri on Iron and Steel, Pravtical and i.>perlmeDtiil," by D, Mujbet, evo, Lon- 

 Vl »M"i WtalCi 



it appeared that a great variety existed, lie was less familiar with that of' 

 Samakolf than with other kinds. The Lancashire hsematite and the Elba 

 ore, were almost identical in composition, except that the latter was slightly 

 magnetic. 



Mr. Taylor stated, that the brown h.xmatite contained manganese. He 

 understood that large quantities of Hlba ore were now conveyed to Corsica, 

 fur the purpose of being smelted cheaply, as charcoal was abundant in that 

 island. Large quantities of Cornish hicmatitc were sent to South Wales and 

 to the other iron districts, for mixing with the argillaceous ores. The price, 

 l>ut on hoard, was about 9s. per ton. At the Birtley Iron Works, (York- 

 sliire,) about one-sixth part of b.-cmatite was used in the furnace. 



Mr. Slatk said, that the quantity of ba;matite ore used in South Stafford- 

 shire was not considerable ; it was mixed with the lean argillaceous ores, and 

 a limited quantity of it was understood to improve the quality of the iron 

 without producing any bad effect on the working of the furnace. The quan- 

 tity which might be advantageously used was governed by the quality of the 

 mine, the form of the furnace, the burden it was considered most profitable 

 to carry, and the pressure of the blast ; it was therefi»re nearly impossible to 

 arrive at any general conclusion on the subject. Tlie use of the haematite 

 ore, however, could not be said to exercise any material influence on the iron 

 of South Staffordshire. In using these rich kinds of ore, it was necessary to 

 lighten the burden, which would of itself improve the quality. The quality 

 of the iron was not a matter of chance, but was more a question of cost 

 being acted on directly by the quantity of fuel used, in proportion to the 

 mine, all other things remaining the same, and iudirectly, by a variety of cir- 

 cumstances, which were carefully attended to by the practical iron-master. 

 The cost price of iron made from mine only, was slated in Staffordshire to 

 amount to £3 or ±'3 ."J*. per ton. The relative quantity of coal, iron-stone 

 and lime-stone, in the improved description of furnaces, introduced by Mr. 

 Gibbons was, for each ton of iron produced, about 50 cwt. of coal at 7«. per 

 ton, 50 cwt. of calcined mine at 12s. or 14s. per ton, and 12 cwt. to 16 cwt. 

 of limestone at 4s. Gd. to 5s. per ton ; to these prices must be added carriaee, 

 labour, and interest of capital. The description of mine referred to, was~of 

 the richer sorts, as gubbin, brown-stone, bluc-llats, balls, &c., whose qualities 

 were however very variable. In some furnaces, the cinder from the forges 

 was mixed in an indefinite quantity, varying with the circumstances under 

 which it could be obtained, or be beneficially employed, in diminishing the 

 cost of the iron. 



The Conegree furnace, on the estate of Lord 

 M'ard, near Dudley, was constructed in a some- 

 what peculiar form, (fig. 1, shows the internal 

 shape and dimensions.) 



The proportions of materials to make a ton 

 of pig iron, were : — 



Coal 2 tons 5 cwt. (or 37 cwt. of Coke.) 



Charred mine 2 „ S to 10 cwt.' 



Limestone .. 13 to 16 



Each charge consisted of — 



Coke . . . . 9J cwt. 



Charred mine .. 12 „ 



Limestone ., .. 4 „ 



As much as 115 tons of cold blast. No. 3 

 pig iron, had been made at the furnace in one 

 week. 



The blowing cylinder was 721 inches in dia- 

 meter, with a length of stroke of 7 feet. There 

 were originally five tuyeres for the introduction 

 of the blast; one muzzle was 2] inches, two 

 others were 2J inches, and the other two were 

 2 inches in diameter. These were subse- 

 quently changed to four luuzzles, of the re- 

 spective diameters of 3i, '2\, 21, and 2 inches. 

 The best working pressure of blast, was 2'i in- 

 ches of the mercurial syphon gauge, which 

 pressure was kept up when the engine made 8^ 

 strokes per minute; with 7 J strokes the mer- 

 cury stood at 2; inches, and with 6| strokes, it fell to 1 j inch. 



Mr. Durham presented a knife manufactured by him from steel, made from 

 the Turkish ores brought over by Mr. Ohancs Dadian. He found, that the 

 steel required to be worked carefully, and to be tempered at a low heat ; but 

 the quality was good, and he had little doubt of its being rendered still bet- 

 ter, by careful manipulation, in manufacturing the iron whence the steel wai 

 converted. 



Fig. 1. 



mmttf 



Interior form and dimenilons of 

 the Conegree Furnace. 



.St. Paul's C'ATnr.niiAL.— The porticoes of the western entrance of this 



cathedral are about undergoing a thorough cleansing and scraping with a view to re- 

 moving the incrustation that has settled on the stone work arising from smoke and 

 dirt. It has not yet been determined whether the wh«le of the western front, aa also the 

 other outer portions of the building, will be scraped and cleansed, the lower part being 

 tried tirst by way of experiment i if successful, the whole of the western front, which 

 forms the principal entrance to the cathedral, consisting of 12 Corinthian columns below, 

 and S of the composite order above, surmounted by a pediment, on the tympanum of 

 which the Conversion of St, Paul is represented, will undergo the same operation. 



