326 



JOCBNAIj OF HOBIICnLICBE AND GOTIAGB OABDKNBB. 



r JUf 1, 1816. 



same consumption of fnel as a saddle boiler o{ the same value. 

 So much, then, for the power of a tabular, as comjiarcd with 

 a saddle boiler. 



2nd. Economy. — I find that a tabular boiler of the value of 

 £20, and a saddle one of like cost, differ but little as to the 

 quantity of fuel consumed. A tubular boiler consumes 1 ton 

 of coke per week for the twenty-six weeks of winter, and 1 ton 

 in ten days durinp the other twenty-six weeks of the year, or 

 44 tons per annum, which at 7s. per ton amounts to £15 8<. 

 A saddle boiler consumes 1 ton per week for twenty-six weeks, 

 and 1 ton in twelve days for the other twenty-six weeks, which 

 for 41 tons of slack coal at 6s. 'Jd. per ton amounts to about 

 £13 Ifo. ihl. Now, this is when the whole of the piping is 

 required to maintain suitable temperatures in stoves, forcing- 

 houses, nud pineries, and this testn the power and economy of 

 boilers more than where the boiler is employed to heat a mis- 

 cellaneous range of hou.ses, some being stoves requiring arti- 

 ficial heat at all times, others viucries that need artificial heat 

 for six or eight months, or it may be only as many weeks, the 

 same remark applying to greenhouses and cool houses generally. 

 For such I lind a tubular boiler consumes 1 ton in ten days for 

 twenty-six weeks, and 1 ton in twenty-one days during the 

 other twenty-six weeks, or 1!7 tons of coke per annum, value 

 £9 9s. A saddle costing £2(( employed for a like purpose con- 

 sumes 1 ton of slack coal in eight days for the twenty-six 

 weeks of winter, and 1 ton in eighteen days for the other 

 twenty-six weeks, or 32 tons per annum, and this at fo. 9ii. per 

 ton amounts to £10 13.s. llff. 



A tabular boiler heating 1500 feet of four-inch piping costs, 

 when employed for heating houses requiring high tempera- 

 tures, £15 8s. per annum ; a saddle boiler heating between 

 600 and 700 feet of four-inch piping, £13 16s. 9</. ; but when 

 the houses to be heated are such as require in part high, and 

 in part low, or occasionally high temperatures, the yearly ex- 

 penses of fuel for the tubular boiler are £9 9s. ; and for the 

 saddle, £10 13s. ll(i. It is not on the score of consuming less 

 fuel that we must look for the economy of saddle boilers, nor 

 in the item of labour, for a saddle boiler takes double the 

 amount of labour and attention that a tubular one requires. 

 Saddle boilers increase the hours of labour, cause much night 

 work, make late goers-to-bed of those who are often required 

 to be early risers, especially if the means are limited to one 

 boiler, and they are besides clumsy, idle, and not economical 

 in working. Any merit they may have would seem to be con- 

 fined to their endurance. 



3rd. Endurance. — From experience of the practical working 

 of tubular and saddle boilers, I can say this much for tubular 

 boilers — 1st, I have not known any removed as inefficient, and 

 replaced by saddle or other descriptions of boilers ; 2nd, They 

 do not fail through the cracking of the " lower rim to which the 

 upright tubes are joined ;" 3rd, Those which have been fixed 

 are still doing that which they were at first calculated to do, and 

 did perform. What I have to say practically of saddle boilers 

 is — Ist, That they are slow in heating ; 2nd, Th.at they require 

 great labour and attention ; and 3rd, That they waste half the 

 heat of the fuel consumed. Again : I have known saddle 

 boilers removed as inefficient, six of them in one instance, and 

 replaced by one tubular boiler, which last consumed no more 

 fuel than two of the saddle-boiler furnaces. 



I really have no further experience of tubular boilers in point 

 of endurance than that I know them to have stood the wear 

 and tear of fire and water for ten years, and in one instance for 

 twelve years, many from six to ten years, and very many from 

 three to six years. In no one instance have I heard any com- 

 plaints of the non-heating of tubular boilers from the deposit 

 of soot and other products of cttmbustion, and I do not think 

 that they are liable to this drawback to anything like the 

 same extent as a boiler heated by coal. It is only reasonable, 

 if a boiler does not heat so quickly after some years as it did 

 when first erected, to attribute the cauFe to the coating of the 

 parts exposed to the action of the fire witli soot and other pro- 

 ducts of combustion resembling coal tar. From experience I 

 am happy to say that there is no deposit of soot, and that no 

 products of combustion resembling coal tar are deposited on 

 any part of a tubular boiler; for as these boilers consume 

 coke smoke is wanting, and therefore there cannot be sooty 

 deposits, nor gas tar, as that is extracted. There is, however, 

 a deposit, and that is of dust, which lodges on the lower rims 

 to which the upright tubes are joined; and the parts imme- 

 diately over the fire have a certain deposit of some kind conse- 

 quent on the action of the fire, but it is one vanishing under a 

 strong fire, or it scales off without its being necessary to clean 



it off, as some do. A saddle boiler, and it of course bums coal, 

 soon becomes coated with soot and a substance much resem- 

 bling coal tar. This and all other deposits vastly imjiair 

 the heating powers of a boiler, and, nnlees cleaned off, the 

 boiler can only be heated by an extravagant consumption of 

 fuel. 



I entirely concur in the views expressed by Mr. Cooper, that 

 tubular boilers are difficult to clear of any dust that may be 

 deposited on the parts farthest from the fire (I cannot entertain 

 the deposit of soot and other substances consequent on com- 

 bustion applying to boilers consuming cokej, but on these dart 

 cannot well rest, as the tubes are vertical, and whatever theM 

 may be is easily removed by employing a brush similar to a 

 bottle-cleaner, with a long twisted wire handle ; but how are 

 wo to clean the side fiues of a saddle boiler, and free those 

 parts of soot, &c. ? The difficulty of doing this renders all such 

 boilers less powerful every day ; no matter how much the boiler 

 is scraped and cleaned, something fastens itself on the surface 

 exposed to the action of the fire which no amount of cleaning 

 effectually removes. This not only affects their efficiency, but 

 their endurance as well, and the decay of the iron is to be 

 measured by the deposit of soot and other products of com- 

 bustion on the iron. A saddle boiler is more liable to this than 

 a tubular one, and how the saddle is to be moro durable I am 

 at a loss to know. 



I am certain that it is not outside a tubular boiler that we 

 must look for that which impairs its efficiency and endurance, 

 but inside for the corrosion of the iron and the lodgement of 

 sediment within the pipe?. This I find is dependant on the 

 water employed, and on the quantity of water passing through 

 the boiler. In a tubular boiler the circulation of the water is 

 much more rapid than in one of the saddle form, and double 

 the quantity passes through it ; I therefore think that a tabular 

 boiler will be sooner choked, owing to the corrosion of the iron, 

 than a saddle one. In that case the former will be less durable 

 than the latter, for its parts being narrower they must neces- 

 sarily be sooner closed. In what other way tubular boilere 

 are likely to be less durable than those of the saddle form I 

 must leave it for others to determine ; but tubular boilers are 

 the most powerful and ecouomical of those of which I have had 

 experience. It is to me a matter of perfect indifference what 

 form is preferred, for boilers scarcely differ in principle, and 

 all have their defects. I look upon perfection in boilers as not 

 yet attained, nor likely to be for a long time, if ever. 



The principle of tubular boilers seems to be the exposing as 

 much surface as possible to the direct action of the fire, and 

 placing as much of it as can well be done in contact with the 

 fire in order to heat the water quickly ; but it is questionable 

 whether employing horizontal tubes is the safest mode of doing 

 80. Horizontal firebai-s and circular rims are calculated to 

 expose a greater surface to the fire than vertical tubes ; but 

 the very thing that facilitates the heating of water hinders its 

 circulation ; for the circulation of hot water in a vertical tube 

 is more rapid than in one that is horizontal. The object 

 should be to heat the greatest quantity of water by placing the 

 parts in contact with and directly exposed to the fire in such 

 a manner that the best effect will be produced, and then to 

 get it out of the boiler as quickly as possible : hence the upright 

 tubes for the upper part of the boiler, they receiving what may 

 not inaptly be termed indirect heat, or that passing up to- 

 wards the ilao after it has been acting on the lower parts of the 

 boiler. 



Of two conclusions, I am certain, 1st, that if boilers are to be 

 made more powerful, it must be by exposing a greater amount 

 of surface, or bringing into contact with the tire more of the 

 surface of the boiler, as is the case with the water-jacket in 

 Clarke's upright tubular boiler. 2nd, That if boilers are to be 

 made more economical of fuel, that economy must be effected 

 by having them so constructed that the greatest resistance is 

 offered to the escape of the heat towards the flue, so as to 

 employ it in raising the temperature of the water within the 

 boiler, instead of allowing it a free jiassage to the chimney 

 to expend itself in space. This obstruction to the escape of 

 heat seems to be happily provided for in the terminal saddle 

 boiler, which is, in my opinion, the greatest stride made for a 

 long time in heating by hot water with the saddle boiler, though 

 even that is by adopting a principle previously applied to tu- 

 bular boilers. I think that the saddle boiler will, notwithstanding 

 that improvement, lack much of the power of a tubular one, and 

 I believe that it will not heat so much piping by one-third as 

 a tubular boiler of the same first cost, and with an equal ex- 

 penditure of fuel. The only advantage I ever saw, or I believe 



