2C4 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[August, 



nearly equal to jV part the weight of the iron; now j^ part the weight 

 of iron of charcoal fused with Swedish charcoal bar iron on the scale 

 of manufacture, affords cast steel of a very high qualitv, which requires 

 careful working at a low red heat to convert it into form; any in- 

 crease of charcoal beyond this proportion would entirely destrov its 

 ductility, either cold or hot. Should an adequate allowance be made 

 for the waste which the charcoal must unavoidably undergo in the 

 crucible, before the affinity is established between it and the bar iron, 

 and for the moisture which, in common with all charcoal, it contains, 

 probably not more than i of its weight becomes united to the iron in 

 the process of fusion. 



In proof that Dr. Karsten's estimate of the proportions of carbon 

 forming steel is excessive, I refer to the celebrated Bergman's analysis 

 of Swedish steel iron and steel. According to him, the proportion of 

 carbon in steel is (or ^j^ P^ir') - - "oO 



Caibon originally in the iron - '12 



Taken up by the iron in passing into the state 

 of steel, equal ^j^ ?*"■' ! -^ proportion very 

 different from those furnished by Dr. Karsten, 

 which range from ^ to ^ij- - - "SS 



A still less proportion of carbon was found in the laborious analyses 

 of four specimens of French steel iron performed by M. Vauquelin, 

 and which seems to have carried the dose of carbon to the opposite 

 extreme. 



*Specimen No. 1, contained of carbon - - 'llOZSO 



Do. 2 do. - - •001183 



Do. 3 do. . . -00789 



Do. 4 do. - . -00043 



I also subjoin a very accurate and interesting analysis made bv Mr. 

 Teimant at Glasgow, and inserted in the Gth volume of the transactions 

 of the British Association, of cast steel made from Danamora iron, 

 which, in point of proportion, coincides with my view of the matter : 



99-28S 

 •190 

 •3S8 

 •134 



Iron 

 Manganese 

 Carbon - 

 Loss 



100- parts. 



This proportion is equal to ^^ part the weight of the steel, and ex ' 

 hibits in a most striking point of view, the minute proportion of car- 

 bon which communicates to iron the varied and enduring properties 

 of steel, without which, or some equally powerful substitute, arts and 

 manufactures would soon become stationary. 



^ . Your's, &c., 



Cole/ord, June 17. d. Mushet. 



P.S. When Dr. Ure revises the article upon the assay of iron ores, 

 I should recommend him to substitute some other glass or flux for flint 

 glass, as it would be inconvenient and perplexing for the juvenile 

 assayist to have to deal with a button of iron over-riding one of lead, 

 the former containing a little lead, and the latter some iron. 



PLATE LAYERS GAUGE LINE. 



/ 



/, four lengths of 16 feet rai's, with the set-ups at o and p. 



n, p, the set-ups on the rail with the line fixed, and shoviing the reel at p. 



g, b, ditto across the ditto. 



m, n, section ot chairs and rail, with the instrument placed. 



r, r, r, top of rail when corrected. 



^n/ 



Sir — I take the liberty of handing to you the annexed rough sketch 

 of a plate-layer's line, &c., for the purpose of enabling the plate-layer 

 to keep nearly a correct gradient on the surface of the rails, between 

 two correct heights, at the distance of four or five 10 feet rails. If 

 you think this of any use, or worthy of insertion in your widely cir- 

 culated Journal, it is at your service, at the same time I beg to say 

 that I am not aware of its ever being applied, but from the best con- 

 sideration I am able to give on its ntility, I am persuaded that it may 

 be applied to advantage, more particularly on railways like the Great 

 North of England, which has so many favourable positions for a great 

 distance in a straight line. 



The instrument can be made very portable, and of a light construc- 

 tion, readily fixed on the cheeks of "the joint chairs, at any distance re- 

 ?|uired, by merely placing the claws of each set-up on them, no other 

 astening being required. 



One of the set-ui)s (or gauge) is furnished with a reel and ratch, so 

 that when the line is wound tight, it will be kept from slackisg; the 

 line must be made fast to the other 'set-up,' and at equal distance 

 from the top of the rail with the other. When the points at a and e, 

 (sketch/) are connected, the instrument may be then fixed on these 

 places ; when the intermediate blocks, &c., at 6, c, and d, may be beat 

 up to the proper height, by gauging from the line to the top of rail, 

 (as per dotted line at/, r;) the line may be so arranged as to stretch 

 from the points a and t, on the surface of the rail, and the intermediate 

 rails then brought up to the line, so that no gauging would be required, 

 but I believe the first process would answer the best. 

 Your obedient servant, 



M. Q. 



Yorl!, June 13, 1841. 



If you refer to page 184, 1 wish you to correct an error in the weight 



* See Mushet on Iron and Steel, and the quarto edition of Nicholson's 

 Journal. 





of chairs, &c., the following is the correct statement, and should have 

 been inserted : — 



Joint chair - - 40 lb. each. 



Middle - - 30 „ 



Check - - 41 „ 



M. Q. 



CHIMNEY FLUES. 



Sir — According to the new Act, chimney flues are, in future, not to 

 be less than 14 inches by 9 inches, or (if cylindrical,) 12 inches diame- 

 ter. Is this meant to apply to the whole extent of the flue ? for if so, 

 all chimney-pots, &c., of less diameter are at once condemned ; as far 

 as such unsightly terminations are concerned, that will however be no 

 loss ; but as experience has proved that when flues exceed a certain 

 size, contraction becomes necessary, at the top at least, to ensure a 

 good draught, if that is henceforth not to be permitted, the fire-places, 

 in order to contain fire enough to rarify the greater column of air that 

 will thus be exposed to its influence, must be enlarged to an incon- 

 venient extent. 



Your opinion on the proper construction of the Act, will oblige your 

 obedient servant, 



A Subscriber. 



N.B. According to Tredgold on this subject, flues seldom ought to 

 be more than 8 or 9 inches in diameter, indeed frequently much less ; 

 and when climbing boys are no longer permitted, there can be no 

 objection whatever to making them of any size that the particular 

 case may require; and indeed there never was any objection, since 

 there is no necessity, even now, for using so barbarous a mode of 

 sweeping as is about to be forbidden by law. 



[We are of opinion that the Act does not apply to chimney-pots — 

 a chimney-pot is not a flue — the flue terminates with the brick shaft. — 

 Editor.] 



