1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



287. 



ON STEAM POWER. 



Sir — Enclosed is the co|)y of a letter addressed to tlie President of 

 the Institution of Civil Engineers, which, should you consider worthy 

 a place in your interesting and vahr.ible Journal, I beg you will 

 make use of it ; my only object in sending it to you, is, that it might 

 direct the attention of those who employ steam-power, to a more 

 economical mode of obtaining that power, at the same time consider- 

 ing that it is the duty of those who have the opportunity of making 

 experiments, to publish any result which would tend to husband one 

 of the greatest resources of our national prosperity. 



I must liowever observe, in justice to myself, that the original letter 

 was forwarded to the President, some days before I rivad, or was even 

 aware, that the Institution had published the first part of their 3rd 

 volume of Transactions, containing Mr. Josiah Parkes' paper on a 

 similar subject, and which you criticised in your last number. 

 I am, Sir, your obedient servant, 



F. Ham, Civil Engineer. 



Rose Lane, Norwicli, %th July, 1839. 



To the President of the Institution of Civil Engineers. 

 Sir — I am induced to address the Institution in reply to Mr. G. H 

 Palmer's paper, since it appears, from your having considered it of 

 sufficient importance for insertion in the 2nd volume of your "Trans- 

 actions," that the recorded duty of the Cornish engines, is still a matter 

 of surprise, in fact, Mr. Palmer seems more inclined to doubt the 

 accuracy of the accounts, than that of his data. 



That it is possible to raise 120,000,000 lbs. one foot high, with one 

 bushel, or 94 lbs. of coal, I do not for a moment doubt ; anil moreover 

 ventuie to say, that even that duty, enormous as it appears, as con- 

 trasted with the ordinary duty of a Boulton and Watt engine, is not 

 the maximum the Cornish engines might be made to perform ; this 

 assertion but ill accords with Mr. Palmer's calculations, which are 

 correct, from the data he assumes, viz. that 7 lbs. of coal are required 

 to convert 1 cubic foot of water at 40" into atmospheric steam, in the 

 boiler of a Boulton and Watt engine, as at present constructed, but 

 which is very wide of the mark, as regards the effect of the com- 

 bustion of 7 lbs. of coal under different circumstances, for instance, I 

 have proved by several experiments made some years since, that 

 7 lbs. of coal will convert into atmospheric steam, at least three cubic 

 feet of water at 40° under peculiar management, which sim])ly consists 

 in exposing a much more extended surface to its action than is usual, 

 and in diminishing the rate of combustion as an example, the same 

 quantity of fuel maintained in combustion for 12 hours, will evaporate 

 at least three times the quantity of water than it would if consumed in 

 2 hours, other circumstances being the same ; this is an effect I have 

 for some years daily produced in an ordinary steam boiler, and have 

 not the slightest doubt, but that with more complete apparatus, and a 

 still slower combustion, nearly double that amount might be obtained ; 

 here then is a solution to the problem, the Cornish engines very seldoni 

 if ever work up to their speed, frequently to not more than a third, 

 the fires are then damped up, slower combustion ensues, and hence the 

 result, with the most complete Boulton and Watt ; on high pressure 

 engines the case is different, rapid combustion is required, in the ab- 

 sence of an extensive boiler surface, to supply the requisite quantity 

 of steam, and promoted to a most wasteful extent, by tremendous 

 chimneys, fans, &c. Intensity and consequently radiation are certainly 

 increased by these means, but neither iron nor copper conducts it in 

 any thing like the same ratio ; in fact, I believe, that when the boiler 

 is highly heated, the water is actually repelled from the surface of the 

 plates, by an atmosphere of caloric, from its not being able to absorb 

 it with sufficient rapidity ; I am moreover confident, that were slower 

 combustion practised, fewer explosions, and a mere tithe of the present 

 destruction of boilers would result, independently of its effecting a 

 considerable saving in fuel, which would most amply repay for the 

 capital invested in extra boiler room. 



Mr. Palmer's paper has certainly been beneficial in exciting inquiry, 

 and has induced me, as I dare say it will others, to institute a set of 

 experiments, on the relative effect of fuel in evaporating, under dif- 

 ferent rates of combustion, and I therefore purpose, as opportunities 

 occur, to investigate the matter in as .philosophical a maimer as my 

 experience will enable me. 



I find also inserted in the same volume, a paper fromMr. Wicksteed, 

 on the effective power of one of the Coniish engines, -.iscertained by 

 weighing and measuring the quantity of water delivered from a depth 

 of 6354 feet. I should liave been much better satisfied with that re- 

 port, had the experiment been continued for a longer period than 

 2i hours, as it is, it can only be regarded as an approximation to the 

 real duty performed by an expenditiu-e of a certain ipiantity of coals ; 

 in the first place, he does not state whether the boilers were feeding 

 No. 23.— Vol. II.— Adoust, 1839. 



or not at the time of the experiment, or that they contained prt"cisely 

 the same quantify of water and pressure of steam after, as before the 

 experiment; secondly, the eye alone is but a very poor judge of the 

 quantity of fuel contained in the furnaces at any period, and a few 

 poimds consumed, either more or less than the assigned quantity 

 would make a very sensible difference in the result ; in fact, I would 

 defy any one, in conducting a similar experiment, and judging from 

 the eye alone, to say witliin 10 or 15 per cent, uuu-e or less, what 

 quantity, not of coal alone, but of combustible matter, had been ex- 

 pended. I do not exactly understand what Mr. Wicksteed means, by 

 saying, that " at the end of 21 hours the fire was lowering and th(! sjjee'ci 

 of the engine decreasing ;" does he mean by the " speeil reducing," that, 

 the engine was a longer time in making the stroke, or, that a longer 

 interval elapsed between each stroke ? for if I mistake not, the interval 

 between each stroke of most, if not all, the Cornish engines, is quite 

 independent of the engine, and governed by a water or air regulator, 

 which is completely imder the control of the engineer, consecpiently 

 the interval between each stroke does not afford any, or the length of 

 time in making tlie stroke sufficiently precise, notice of the 94 lbs. of 

 coal having been expended or otherwise. It appears that during the 

 experiment the engine was not making quite five strokes per minute, 

 had it been working at its maximum speed, he would have found his 

 103 millions of pounds actually raised one foot high reduced to about 

 50, or perhaps even so low as 20 millions ; considering the state of 

 the boilers and Hues, which he states "had not been cleaned for eleven 

 months," arising from an increased rate of combustion being recjuired 

 to maintain the ilensity, and supply the increased rate of expenditure 

 of the steam, otherwise how can the great discrepancy between Capt. 

 Lean's reports of tlie maximum and average duty of the Cornish 

 engines, and Mr. Wicksteed's experiments be accounted for, and if 

 the latter gentleman expects the engine he is erecting at Old Ford, to 

 raise 120 millions of pounds one foot high, with 94 lbs. of coal, at its 

 proper speed, without consideralily increasing the boiler surface, so as 

 to admit of slow combustion, he will be most grievously disappointed. 



These remarks are made with the highest respect for Mr. Wick- 

 steed, and as our joint object is to elicft truth, I trust they will be 

 received in good part, and serve as an introduction to my better ac- 

 quaintance with him, and allow me to say that an experimenter cannot 

 be too precise in stating the particulars of the precautions he adopts 

 to ensure accuracy, for they not only serve as a record of his ability, 

 wdiich may ilo him honour, but render the report itself the more 

 valuable, inasmuch as science advances, truth or error can be more 

 easily deduced from it. 



I am, Sir, your's very respectfully, 



Frederick Ham. 



Rose Lane, Xorwicli, May 2, 1839. 



SUBAQUEOUS EXPLOSIONS. 



We are very glad to see that Mr. Bethell's interesting paper on 

 blasting rocks, &c. under water by the aid of galvauisni, read before 

 the Institution of Civil Engineers, accompanied by experiments, and 

 first reporteil in our Journal in May last year, (p. 19s, Vol. I.) is likely 

 to lead to the greatest practical use and benefit. Colonel Pasley, we 

 are happy to find, has entered upon this investigation, and his well 

 known perseverance and accuracy in experiments will, we trust, lead 

 to the general adoption of voltaic electricity for the purpose of sub- 

 aqueous and subterraneous explosions. On this subject a very in- 

 teresting paper, entering minutely into details, appeared in the last 

 June number of the Uuittd Service Journal, from which we gi\-e the 

 following extract: — 



" We shall now proceed to state, as far as has come to our knowledge, 

 what has been done in this country respecting the applicati<m of vol- 

 taic electricity to practical purposes — that is, if supported by detailed 

 and well-authenticated evidence as to when and where, without re- 

 garding the mere assertions of any individual, inyespect to his having 

 blown off the decks of sunken vessels by the voltaic battery, such as to 

 the best of our recollection we have read in a scientific journal of re- 

 putation ; but in which neither the names of those wrecks, nor the 

 time or place of any of his operations, were specified; and therefore 

 our noticing tliem could give no positive knowledge or satisfactory 

 information. It is well known that small charges of gunpowder have 

 often been fired by this means in lecture-rooms, or in scientific insti- 

 tutions, in this country, both in air and in a buiket of water; and 

 nothing is easier than to do so in a room, where failure can scarcely take 

 place without extreme neglect, as no accidents are to be apprehended 

 from the elements. But to secure a charge of gunpowder that is to 

 be fireil by voltaic electricity, at a great depth of water and in a rapid 



