28 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Jan" 



having lately been much canvassed, in consequence of numerous fires 

 having been ascribed to this cause. Mr. Gurney had found tha t ea 

 can be carried through the air along a pipe, a distance of forty feet, 

 sufficient to melt lead, and that these results took place with the low 

 pressure pipes. The safety valve in certain cases was no protection. 

 On placing stop cocks at certain distances along apipe communicating 

 with a boiler, he found that when the temperature was sufficient to 

 bum saw-dust, an invisible and inflammable elastic fluid escaped. He 

 advised that six inches of the circuit in pipes for heating be made of 

 lead. A new cement has been used at Manchester called Lithic ce- 

 ment, it is as hard as stone, and has a face as smooth as earthenware. 

 It would be useful in the metropolis where our cements scarcely merit 

 the name. In architecture generally, we were glad to see a gradual 

 movement onward, and though the progress is slight, it is ol that kind 

 which augurs well for its continuance. 



E. H. 



December 1841. 



BEVIEVrS. 



Practical Essays on Milbvork and other Machinery. By Robertson 

 Buchanan, afterwards improved and edited by Thomas Tredgold, 

 C. E., and now re-edited with the improvements of the present age, 

 by George Rennie, C. E., F.R.S., &c., 2 vols. 8vo., with numerous 

 plates. London: John Weale, 1841. 



The name of Rennie would be embalmed in the history of millwork 

 improvement, did it not possess still nobler claims to immortality. It 

 was the father of the editor of the present volumes who first gave a 

 real practical efficacy to those philosophical speculations which ascer- 

 tained the true geometrical configuration of the elementary parts of 

 wheelwork that was essential to produce uniformity of impulsive action 

 and durability of operation. The millwork of the Albion mills was 

 the first public manifestation of the late Mr. Rennie's abilities, and the 

 improvements introduced by him upon tliat occasion gave an impul- 

 sion to millwright operations, such as tlie art had never before ex- 

 perienced, and of which it still feels the beneficial effects. It is little 

 more than half a century ago that the teeth of all the miliwheels in 

 this country, with a few inconsiderable exceptions, consisted of no- 

 thing better than round wooden pegs. Smeaton accomplished some 

 amelioration. But it was reserved for Rennie to give to miliwheels 

 their present form and structure, and the achievement would have 

 been sufficient for his fame, had it not been thrown into the shade by 

 those more brilliant tiiumphs of genius by which he is now almost 

 exclusively remembered. 



In opening a treatise upon millwright operations which has been 

 published under the supervision of a son of this distinguished engi- 

 neer, and who is himself already honourably known as a scientific and 

 practical mechanician, our expectations were naturally commensurate 

 with the auspicious quality of the circumstances under which the work 

 had been produced. We cannot say that these expectations have 

 been wholly disappointed. There is a considerable infusion of infor- 

 mation in these volumes of the highest utility, and there is evidence 

 of extensive erudition, and an intimate acquaintance with the subject. 

 Yet the execution of the work is by no means satisfactory. There is 

 a want of vigour and of unity discernable throughout the whole 

 treatise — the needless prolixity of some of the chapters is extremely 

 fatiguing to the reader — obscurity is not unfrequently produced by 

 excess of simplification ; and the arrangement, notwithstanding the 

 exertions of an excellent analytical table of contents, is very much like 

 the Gordian knot which no one can disentangle. We do not remem- 

 ber to have met with any work which required a more painful exer- 

 cise of attention on the part of the reader, and this attention is not 

 rendered necessary by the difficulty of apprehending recondite investi- 

 gatious, but by the difficulty of ascertaining the mutual relation of the 

 several parts of the discourse— of unwinding the tangled thread of tlie 

 enquiry. In fact these volumes can scarcely be regarded as a connected 

 systematic treatise, they are rather a disorderly collection of mis- 

 cellanpous papers of varying quality, from which the reader may make 

 a selection, and which he must arrange for himself. In addition to 

 Buchanan's original work with editorial notes and emendations, and 

 two long papers in the form of appendices, besides supplementary 

 definitions and other irrelevant matter, we have avast number of "ob- 

 servations," "general observations," and "supplementary observa- 

 tions,"— the greatest part of them trite and trivial, mingling with the 

 text, and dancing through every page in the most disorderly and fan- 

 tastic array. The thread of the discourse is broken at every step. 



and the reader is almost tempted to throw a work aside which de- 

 mands a severity of labour that bids fair to rival the toil of Sisyphus. 



Another source of considerable perplexity is the absence of all 

 means of determining what portions of the work are due to the origi- 

 nal author, and what to his respective editors. Additions and com- 

 mentaiies are mixed up without scruple with the original text, so that 

 we are utterly at a loss to know, unless by a reference to previous 

 editions, to whom we are paying attention. After having listened for 

 some time to Mr. Robertson Buchanan, we find that by some undivulged 

 metempsychosis, he has been for some time changed into Mr. Thomas 

 Tredgold, or Mr. George Rennie. In page 5, for example, it is ob- 

 served, "Were the teeth of wheels infinitely small, their action would 

 be regarded as that of cylinders simply touching, having the property 

 required. The finite and sensible teeth given to wheels will therefore 

 be of the most advantageous figure when one wheel conducts another, 

 as if they simply touched ; or, when their pitch lines have in every 

 part of their revolution equal velocities. That teeth have this pro« 

 perty when formed in a certain manner will be evident from the following 

 proposition and its connexions." This quotation we find by a note at 

 the foot of the page, to be a part of Buchanan's text, and we naturally 

 conclude that the text continues to be Buchanan's until we receive 

 some intimation to the contrary. But we have not advanced above a 

 dozen lines further before we meet, "Before proceeding with our 

 author, it will be," &c., whereas we imagined it to have been Me 

 author himself, we bad all the time been listening to; 



At what point in the compass of a dozen lines Mr. Buchanan has 

 been transformed into Mr. Tredgold or Mr. Rennie, we have no means 

 whatever of ascertaining. We are unable to distinguish between what 

 is said by the one person and what by tlie other person without collat- 

 ing the different editions— without, in fact, ourselves editing a book 

 we merely wish to read. In page 26, we read, "To make that part 

 of a tooth which is within the pitch line or proportional circle, a 

 straight line as proposed by our author, seems to be the most advan- 

 tageous form ;" and in page 27, " When part of the action takes place 

 before the teeth arrive at the line of centres, the method of forming 

 teeth proposed by our author (Art. 41), seems to be equal, if not supe- 

 rior to any other ;" yet the article from which these quotations are 

 taken are a part of the text, in no wise distinguishable as such from 

 Art. 41. In page 41, we find, "It has been mentioned to me that the 

 following rule in order to determine the length of the teeth of wheels 

 is employed by the ingenious Mr. Murray of Leeds ;" and a note at 

 the bottom of the page accidentally shows us that this is a part of 

 Buchanan's text, and in page 45, we meet, "On this Tu\e Buchanan 

 remarks that it does not seem founded upon any satisfactory principle." 

 In page 34, "Sometimes it may be requisite to have but few teeth in 

 the pinion. In such cases, in the conducted whether wheel or pinion, 

 Buchanan preferred staves to teeth;" and in page 3(3, "Everyone 

 considerably experienced in wheel-work knows that when a pinion 

 comes to be considerably worn, the friction is greatly increased. 

 Whereas no such thing happens to the trundle." In a note referring 

 to this passage, it is said, " This is a mistake, as trundles inconse- 

 quence of the surfaces of contact being small, become soon indented 

 by pressure, and cease to turn round in their sockets;" but whether it 

 is Mr. Buchanan who makes this mistake or Mr. Tredgold, we have 

 no means of finding out. We are inclined, however, to believe it is 

 the latter gentleman, as Buchanan is usually distinguished by name, 

 and five lines further on from the text we have last quoted, we meet, 

 " It appears, however, to Mr. Buchanan, that a wheel might be made 

 which would combine the advantages of both the pinion and trundle." 



We will not tire our readers with further quotations upon this head,, 

 we might extend them indefinitely, and it is no extenuation to say that 

 the value of the information rendered is unaffected by the name of the 

 preceptor. The confusion of persons might be excusable if it v ere 

 essential to achieve some highly beneficial result, but only upon that 

 untenable supposition. The perplexity it occasions to the reader is 

 extremely disagreeable — it creates moreover a species of responsibility 

 such as might be expected to arise from anonymous authorship that 

 is by no means beneficial or expedient. That in re-editing a work 

 relating to the practical arts or inductive sciences, it is right to make 

 such additions and corrections as are answerable to the progress of 

 improvement, we do not deny. But we deny to any editor the right 

 to mingle his own commentaries or speculations with the original text 

 in such a manner that they are indistinguishable from it. What would 

 have been the fate of all ancient authors if their successive editors 

 had assumed such a prerogative ? If Mr. Buchanan undergo many 

 such purifications, we fear he will be sublimated altogether. Where 

 a work by the suppression of any palpable errors, and the addition of 

 separate supplementary notices, is incapable of being rendered an- 

 swerable to existing conditions, it is much better to reject the piece 

 of antiquity altogether in favour of a new treatise. There is little 



