6S 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[Novembkr, 



Columns No. 2, 3, 4, 5, and 6, require no farther explanation than has been 

 already given. 



Column No. 7, shows the average ntimhcr of strokes made by the engine 

 per minute during the time of the experiments. 



Column No. 8, shows the effective power of the engine, and is obtained by 

 multiplying the weight of water lifted eaeh stroke (which was equal to 

 1920-j^) by the pressure shown in column No. 6, and by the strokes per 

 minute shown in column No. 7, the product being the number of pounds 

 weight raised I foot high per minute, which, divided by 33,0001b., will give 

 the horses' power indicated in column No. 8. 



Column No. 9, shows the quantity of water (in decimals of a cube foot) 

 required per hour to pass through the cylinder and steam jacket in the form 

 of steam to produce one horse's power, and is obtained by reducing column 

 No. 4 to cubic feet, and dividing by the hours given in column No. 3, and 

 again dividing the quotient by the horses' power represented in column 

 No. 8. 



Column No. 10, shows the proportional quantity of water in the form of 

 steam required per horse's power under different states of clothing or ex- 

 posure of the cylinder, &e., as described in column No. 12. 



Column No. 11, shows the proportionate saving of water by clothing the 

 cylinder as described iu column No. 12. 



Upon examination of the results shown in the Tables, a description 

 of which has just been given, it will be seen in Table No. 2, that when 

 the boiler was clothed with one coat of Bo radaile's Patent Felt, that 

 the evaporation was a little greater tlian when clothed with five coats 

 of hop sacking. When clotlied with In-o coats of felt it was not su- 

 perior to one coat of felt, but when clotlied with three coats, the evapo- 

 ration was 1-jif per cent, greater; and when one coat of felt liad been 

 laid on the top of the flues, on the flag stones round the boiler, the 

 evaporation was increased 8^77 per cent., and when the boiler was 

 clothed with four coats, and the top of the flues with two coats, the 

 evaporation was increased -^ per cent, only ; from this it would ap- 

 pear that to produce a considerable saving in fuel, it is necessary to 

 have at least three coats of felt, and that the top flues should be coated 

 with at least one coat of felt. 



Upon examination of Table No. 4, it will be seen, (hat to obtain the 

 greatest effect of saving from casing with Patent Felt, that not only 

 the steam-jacket and steam-pipes should be clothed, but also the 

 cylinder-cover, and steam-nozzle. Tlie result of these experiments, 

 which an examination of the tables will prove to have been carried on 

 upon a large scale, each trial being continued for several days, shows 

 that by properly clothing the boilers, steam-pipes, and flues, with 

 Borradaile's Patent Felt, a saving of fuel of 10^ per cent, may be 

 elfected ; and by properly clothing the cylinder-steam-jacket, steam- 

 pipes, nozzle and cylinder-cover, a s iving of 15 per cent, is eft'ected in 

 the quantity of water converted into steam to produce a given effect ; 

 and consequently, the combined result is equal to a saving of fuel of 

 25^ per cent. 



Although the saving in fuel effected may be considered as the 

 greatest advantage in using the Felt, yet there are others of no slight 

 importance which should be noticed. 



1st. The saving in the repairs of the boilers ; supposing two boilers 

 equally well made, of equally good materials, uniler which the same 

 quality of coals is burnt, and in which the same quality of water is 

 used, it is very certain that the wear and tear of the two boilers will 

 be in proportion to (he quantity of fuel burnt under them ; now if the 

 same effect can be produced by using 25 per cent, less fuel under one 

 than under the othei, the wear and tear will be 25 per cent, less in 

 one than in the other; now although the actual amount of saving can- 

 not be estimated, as it must depend upon the quality of materials and 

 workmanship employed, which varies in almost every boiler, never- 

 theless, that it is a matter of importance will strike every one who 

 ha.s had to do with repairs of boilers. 



2ndly. In steam-vessels it must be remembered that a reduction in 

 the weight of coals is equivalent to an increase of toimage, or in other 

 words, supposing a foreign vessel whose cylinders, steam-pipes, and 

 boilers are unclothed, carries in the course of twelve months 401JU tons 

 of coals as fuel for the engines, a reduction in the fuel of 25 per cent, 

 will enable them to carry lOOU tons extra weight of cargo. 



3rd. Reduction in the cost of labour in working the engines, espe- 

 cially on board steam-boats. Upon this point it is not necessary to 

 say more than that, by reducing the quantity of fuel to be used, and 

 reducing the temperature of the engine room, and stoke hole, the 

 labour of the engine men and stokers will be considerably less, and it 

 is very evident a considerable saving may be made in this item of ex- 

 penditure. 



4th. If judiciously applied, the felt will prove a great safe-guard 

 against fire, as it will be seen, by reference to Mr. Aikin's experiments, 

 an account of which is appended to this report, that it may be exposed 

 to a temperature of 4011" Fabi. without being aB'eeted. 



EsPENXE OF Clothing. 



This, of course, must vary according to the size of the engine and 

 boilers, whether land or marine, engines, &c. &c. ; the cost, however, 

 of clothing the engine upon which the trial was made, and two boilers 

 with four coats of felt, the engine work covered with green baize 

 oil-cloth, and the boiler with canvas, as herein before described, was 

 £'IG; the engine working 12 hours per day exposed, or not clothed, 

 would consume llOU tons of small Newcastle coals per annum, which, 

 at 17s. per ton would be equal to £03.'); 25 per cent, saving on this 

 would be £233 158. or 251 per cent, profit upon the outlay of £915. 



Durability of the Felt. 



It has been the general practice to coat the boilers, pipes, and cylin- 

 ders with a mixture of white lead, alum, Paris wliite, and liuseeil oil, 

 before the first coat of felt is laid upon it, with the intention of pre- 

 venting the felt from being scorched from direct contact with the 

 heated metal ; and it has been said that the fire which occurred in the 

 Great Western steam ship when in (he Thames, on her first voyage, 

 was occasioned by the oil hi this composition catching fire ; to ascer- 

 tain how far the use of this paint was necessarv, and also what heat 

 the felt would bear without being injuriously affected, I requested Mr. 

 Arthur Aikiu to try some experiments, and favour me with his opinion 

 on this matter, and beg to refer you to his letter, which is appended 

 to this report, and which to me appears most satisfactory ; I also beg 

 to draw your attention to his valuable suggestion of a new mixture to 

 be applied in the place of that used at present in places where it may 

 be found necessary, as being much more efficacious. With a view of 

 showing the saving which may be effected by the use of the patent 

 felt, 1 have calculated the Table No. V., shewing the saving in annual 

 expence in proportion to the consumption of coals per annum, and the 

 price per ton. 



In conclusion, I beg leave to say that I had not, before I tried these 

 experiments, an idea that the saving would be so great as it proves to 

 be; the experiments have been, however, conducted with so much 

 care, each series has been continued for so long a time, and the coals 

 used having been from the same cargo, (hat 1 have not the slightest 

 doubt any person clothing their boilers and engines in the same man- 

 ner, and to the same extent hereinbefore ehscribed, will at once effect 25 

 per cent, saving in fuel, or in case of a boiler and steam pipes alone 

 where an engine is not used, a saving of 10 per cent. 



THOM.4.S WiCKSTEED, 



Civil Engineer. 

 Old Ford, August Mlh, 1840. 



Report of Arthur Aikin, Esq., F.L.S., F.G.S., &c. 



My dear Sir — You inform rae that it is customary to cover the outside 

 of steam boilers with a paint composed of lead, oil and alum previous to ap- 

 plying the coating of felt. This you say is done with the intention of pre- 

 venting the felt from being scorched by direct contact with the heated metal 

 of the boiler. You require my opidion if it is necessary to interpose any sub- 

 stance in order to avoid injury to the felt, and likewiae inform mc tliat in 

 one instance a fire was said to have originated from the oil paint becoming 

 overheated. 



With the view of answering your inquiries in a satisfactory manner, my 

 first object was to ascertain the utmost degree of heat which felt is capable 

 of hearing without injury. For this purpose 1 put several pounds of mercury 

 in an iron basin, and then placed another smaller basin on the mercury — in 

 the smaller basin I put a layer of felt, and a])plied pressure to (he upper sur- 

 face of the felt suiiicient to force the bottom of the iron basin iu wliich it 

 was contained, so deep in the mercury that there was only about half an inch 

 of mercury between the two basins. A pot of burning charcoal was then 

 placed below the larger basin, and a* mercurial thermometer graduated to 

 COO Fah. was dipped from time to time in the mercury to ascertain the tem- 

 perature. When the heat had risen to 300 Fah. a small piece of felt was 

 immersed in the mercury between the two basins, and was withdrawn occa- 

 sionally as the heat increased, in order to observe the effect produced on it. 

 Up to the temperature of 440" or 450°, the felt appeared to suffer no injury, 

 the colour remaining unaltered ; but from 450° to 480° the colour first became 

 deeper, the elasticity of the fibre was destroyed, it then became nearly black, 

 and at the same time gave out the odour of burning hair. The hot charcoal 

 was then removed, and on examining the felt which was in tlie small basin, 

 it gave out, while warm, a burnt odour, and the surface in contact with the 

 iron had become of a dark brown colour, as you may see in the specimen 

 wlilch accompanies this report. 1 consider therefore the heat of 440 Fah. as 

 the highest to which felt can he exposed without injury, even for a short 

 time (for my experiment did not continue above an hour), and if the heat 

 were continued for several days, it probably ought not to exceed 400 Fah. If 

 therefore the external heat of a steam boiler is liable to rise to 400 Fah., it 

 would be prudent to interpose some substance between the surface of the 

 boiler and the felt, but for this purpose oil paiut with a basis of Utharge, red 



