1850.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



139 



from ourselves, after a due examination of the merits of the 

 labours whidi haie put us in possession of the conflicting oi)ini(ins, 

 and, in tlie majority of cases, valuable evidence embodied in the 

 Reports of the several Commissions, instituted at different times 

 with a view to ameliorating our sanitary condition, that tliough the 

 progress of improvement has been slow, it has been .sunt — though 

 not marked by many of the results we had a right to anticipate. 

 That so great a delay has occui-red, is not, therefore, to be attri- 

 buted to the want of talent and exertion on the part of the public 

 bodies appointed to examine the special means requisite ; or of 

 ability — so far as the resources of the present existing state of cer- 

 tain branches of science admit of — of our professional men, a 

 large portion of whose contributions embody, perhaps, the most 

 valuable additions that have been made of late years to engineer- 

 ing science generally; but in some measure to the want of such 

 data as cannot be obtained from the testimony of former experience 

 or former practice, and concerning which the Commissioners have 

 only been able to elicit conflicting opinions, the more difficult to 

 decide upon, there being at least a somewhat general agreement 

 among the witnesses, as to tlie inappliancy of received formula? as 

 guides for the framing of future plans — thus setting aside not only 

 the practice, but also the received theory of former years. 



The summary of the questions to be settled before any proposed 

 system can be generally deemed ad\isable, includes, on account of 

 this disagreement of opinions, a great number of heads, respecting 

 which furtlier investigation becomes consequently necessary; and 

 in order to obtain indisputable conclusions on the majority of these 

 points, such investigations ought to be founded on trials, when 

 possible, of the respective merits of the diff'erent proposals made 

 for effecting the same objects, where so proposed, or deduced from 

 cori-ect experiments when tlie same practical means are advocated; 

 but a diversity of opinions exist respecting the theoretical means 

 of application of such pi-actice, whether in the shape of formulae 

 or otherwise, to varying circumstances, simply dependent on mere 

 local circumstances. 



For instance — Mr. W. Hosking^, Professor of Architecture in 

 King's College, and Mr. John Phillips', C.E., Surveyor of Sewers, 

 advocate tlie oviform sewer with the small end downwards; on 

 the other hand, Mr. Joseph Gwilt -, Architect, Surveyor of the 

 Lambeth District of Sewers, and author of varioiis works, one on 

 the strength of arches, which "has passed through three editions;" 

 and another, a complete encyclopaedia of architecture — of construc- 

 tion in all its branches, prefers turning the oviform drain of the 

 abovenanied gentlemen upside down; and argues the advantages 

 of the big end over the little end for the lower side of the sec- 

 tion, but favours more particularly tlie vertical-sided form with 

 semicircular top and bottom; while the late Mr. Butler Wil- 

 liams'', C.E., and Mr. Henry Austin", Secretary of the Board of 

 Health, expi-ess their opinions in favour of circular drains. Each 

 of these advocacies is duly backed by mathematical reasons of 

 some kind or other (we say of some kind or other, since they can- 

 not possibly all be correct); and as the matter to which they relate 

 belongs to the 7)iitc<l instead of the pure mathematics, it becomes 

 extremely difficult, nay, impossible, without actual proofs of demon- 

 stration, to give such a judgment on any such point as would be 

 deemed satisfactory by all. 



In the mere examination of a witness, there are diflSculties to 

 contend with. The following is asked: — 



" Have you had any experience, or would you state it as a result of which 

 you have no doubt, that an eicg-shaped sewer, with the broad end down- 

 wards, will, with the same run of water, discharge more quickly, and keep 

 itself clean hetter tlian an egg.shaped sewer with the narrow end down- 

 wards ? — I should say it would clear itself better because there would be less 

 friction upon a circle tlian there would be on the parts of an ellipse '." 



Hero we have a question, which at first sight seems clear, 

 important, and well put; but which is, in point of fact, essentially 

 faulty, inasmuch as the answer is a variable one, dependent on the 

 very condition left out, viz., the height of flow in the oviform sec- 

 tion, "the same run of water" not being a sufficient condition, 

 admitting at it does of the very opposite answei-s, according to the 

 circumstances of "quantity" 'left out. We pi-oceed with the 

 evidence: — 



" Do you not think, that is a fact which may be determined by actual 

 experiment ? — No doubt it may." 



"And ought not it to be ? — I ca n see no objection to it whatever." 



- First Report of the Hjnlth of Towns Commissioners. Qaest. 36a, p. 39. 



3 First Ri-poit of the Metropolitan Sanitary Commissioners. F.vidence, No, 13. 



* First Report of the Metropolitan Sanilary Commission.-rs, Evidenee, Nj. 20. 



5 First Report of the Health of Toiens Commissioners. Quest. .M28. p. ,130. 



c First Report of the Metropolitan Sanitary Commissioners. Evidence, No, 2.'J. 



~ First Reporter the Metropolitan Sanitary CommissiODers. Evidence, No. iO, p. 101. 



A dangerous question cautiously answered. A simple unguarded 

 affirmative answer would have been an admission of doubt on the 

 part of the witness; but here the answer implie.s, "If you wish it 

 for your own satisfaction, well and good: as to myself, I am per- 

 fectly satisfied as to wliat the result would be." Consequently we 

 (d)taiii a decided unconditional answer to a question, which, not 

 being sufficiently explicit, only admits of a variable one. 



We have brought forward an instance, out of many others, to 

 show how difficult it is to deal satisfactorily w itli matters of this 

 kind; and how essential it is to do our utmost to divest ourselves 

 of all prejudices we may possess for or against any opinion at all 

 likely to influence our decision. Unfortunately, ours are many 

 andflooply-rooted. Our pure mathematics are indisputable — their 

 proofs incontrovertible; but their practical application to the arts 

 of life antl civilisation, requiring data derived from observation 

 and experiment, engenders difficulties which render the investiga- 

 tion of the applied sciences often perplexing — too often intractable. 

 Hence the origin of what are termed "false theories"^ — of the 

 diffidence generally shown towards opinions purporting to be new — 

 hence the great distinction made between theory and practice — 

 itself a false notion. The mixed sciences, as the term implies, 

 require, less or more, certain admixtures of the "pure" and the 

 less certain — of the theoretical antl the practical; any bias of the 

 mind, therefore, in fa\our or against either of these, theory or 

 practice, as regards "applied" cases, does not only come under the 

 head of prejuilice, but is, besides, a false impression; since, cor- 

 rectly speaking, neither can be used independently of the other in 

 any such application. We can no more progress in the theoretical 

 investigation of any branch of mixed science, without experiment 

 and observation, ^iz. practice — requiring, as we do, "new" facts 

 to build upon — than we can hope to obtain "general" conclusions 

 from mere practice, without inductive reasoning; since "expe- 

 rience cannot conduct us to universal and necessary truths: not 

 to universal, because she has not tried all cases — not to necessary, 

 because necessity is not a matter to which experience can testify." 

 And, therefore, we must insist as strongly against the practice not 

 founded on theory correctly induced from facts, as we do against 

 theory not founded on facts correctly deduced from experience. 



When we consider the many difficulties attending the investiga- 

 tion of "trutli" — when we reflect on the slow progress of some of 

 the inductive sciences — on the too frequent want of necessary 

 data — and that hydraulics is, perhaps, of all the physical sciences, 

 that respecting whicli the least satisfactory results have been 

 obtained, after having occupied the attention of some of the 

 leading minds science can boast of — when we bear in mind the 

 difficulty of introducing' new views, however plausible — of the 

 prejudices existing in favour of received practices, however faulty, 

 we cannot wonder that the question of the means of an efficient 

 drainage of the metropolis is still an undecided one; although, 

 from a careful examination of the labours of the Sanitary Com- 

 missioners (as we have already said), we cannot but allow that they 

 have done much that was necessary towards the end in view— much 

 for which tlie next generation of engineers will thank them. 



In consequence, partly, of the difficulties we have thus briefly 

 alluded to, thirty years have elapsed, as we said before, since Mr. 

 Martin's attention was first directed to the three most important 

 questions connected with the drainage of Loudon, without any 

 decision having been come to respecting either of them, though 

 the labours instituted by the legislature have, of late years, been 

 incessant. His opinions, however, were not published until 1828, 

 when his "first suggestion for not only reliexing the river from 

 its impurities, but preserving the sewage for agricultural purposes," 

 appeared. In 1830, Mr. Aiiiger, the then conductor of the Gar- 

 deners' Mai/axine, published in that work his plan for "preserving 

 the purity ot the Thames, by constructing covered dr-iins along 

 the sides of the river to receive the minor drainage. " Shortly 

 afterwards, the proposals for improving the banks of the river 

 were submitted to the Committee for Improving the Navigation of 

 the River Thames, whose Report was presented to the Court of 

 Common (council, 3rd August, 1832, and contains some useful 

 information on the questions of embanking, and the formation of 

 quays. In July, 183!, Mr. Martin presented to the Select Com- 

 mittee of the House of Commons, appointed to inquire into the 

 law respecting Metropolitan Sewers, his plan, published in 1828, 

 the objects of which were described to be — "1st, to materially im- 

 prove the drainage of the metropolis; 2nd, to prevent the sewage 

 being thrown into the river, and to preserve in its pui'e state the 

 water which the inhabitants are necessitated to use; 3dly, to 

 prevent the pollution of the atmosphere by the exhalations from 

 the river, and the open mouths of the drains; and, 4th, to save 



20* 



