1842.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



425 



Bhint's Civil Engineer and Practical Machinist. By Charles 

 John Blunt, C. E., &c. London : Ackerinan and Co. 



To describe the contents of this work is the best way to sliow its 

 value. They consist of six copper-plate engravings the size of im- 

 perial, taken from the working drawings from which the machines 

 were actually made, which renders them authentic records of the 

 machinery of some of our first engineers. We could have vi'ished, 

 however, to have seen a little more finish to some of the plates, and 

 the dimensions more generally given ; for instance, we will allude to 

 the engraving of the Thames Tunnel, in which the inverts appear to 

 abut upon nothing in the centre, and the brickwork of the shaft ought 

 to have been shaded or hatched. 



The first plate contains the drawings of a marine dredging and 

 excavating engine, and deepening machine, employed in the forma- 

 tion of harbours, constructed by Messrs. Rennie, being the engine 

 erected for the harbour of Barcelona; tiie plate is 4i in. long, and 

 18 in. broad ; many of the details are delineated upon an enlarged 

 scale. Mr. Blunt, contends, that the late John Rennie was the original 

 inventor of the dredging machine, but does not state the year he first 

 introduced it at the Hull Docks. This statement is at direct variance 

 with an article that appeared in the Journal for January 1830, page 9, 

 vol. 11, by Mr. Thomas Hughes, wherein he claims the invention as 

 that of his father, who used the dredging macliine off Woolwich, 

 in 1S04. Now the question is, did Mr. Rennie introduce the machine 

 prior or subsequently to that date ? Mr. Hughes says subsequently, 

 which remains to be disproved by date. There cannot, however, be 

 a question that the late Mr. Rennie, together with his talei)ted sons, 

 have brought the machine to that great perfection it has now at- 

 tained. 



The second and third plates represent a steam engine for driving 

 machinery and mills by Messrs. Rennie. The fourth co. tains draw- 

 ings of a direct action marine engine, with side guides, and the sec- 

 tion of an iron steamer, also by Messrs. Rennie; we have here to 

 find the same fault as we have done in another review givon in the 

 present Journal, for omitting to give the sections showing the interior 

 of the engines, and likewise some details and dimensions; without 

 them, it is useless to give mere views of the exterior. We believe 

 this vessel and engines were tried by Messrs. Rennie during the last 

 season, when the vessel proved to be one of the fastest steamers on 

 the river Thames. The fifth plate is the Tliames Tunnel, containing 

 a longitudinal section, showing the archway, the shield, the driftway, 

 and the formation and sinking of the large shaft on the Middlesex side 

 of the river. The sixth plate is devoted to a fifteen ton crane, con- 

 structed by Messrs. Rennie. 



We think we have shown enough of the work to prove its im- 

 portance as a national record, and a work of value to the engineer. 

 We trust, however, that in future more attention will paid to tlie en- 

 gravings, and likewise to the insertion of the details, which will 

 greatly enhance the value of the worfc, and make it one of reference 

 for the profession. 



Tlie Mechanical Principles of Engineering and Architecture. By 

 the Rev. Henry Moseley, M.A., F.R.S., Prof, of Nat. Phil, in King's 

 College, London. London : Longman & Co., 1&13. 



Professor Moseley's previous works have at various times come 

 under our notice, and we have felt it our duty to express our feelings 

 of the spirit of research and enterprise with whicli the author has 

 exerted himself for the promotion of constructive science. Placed 

 at the head of an important department of collegiate instruction, 

 Mr. Moseley has fell the necessity that exists for the adaptation of 

 scientific principles to the practical pursuits of the engineer and ar- 

 chitect, with whom the progress of new combinations and new con- 

 structions renders it imperative that the classbooks and works of 

 reference should be frequently remoulded and made applicable to the 

 wants of the day. It is in union with these requirements that Mr. 

 Moseley has been induced to undertake this work, in which the ap- 

 plication of mechanics in the varied pursuits of the engineer and ar- 

 chitect is taken into consideration. Under the head of dynamics, 

 Mr. Moseley has directed his attention to the subject of ditlt/, for 

 which he proposes to substitute the term work, iu imitation of the 

 French ' travail ;' he observes, that " the English word ' work ' is the 

 obvious translation of 'travail,' and the use of it appears to be re- 

 commended by the same considerations. The work of overcoming 

 a pressure of one pound through a space of one foot has in this 

 country been taken as the unit, in terms of which any other amount 

 of work is estimated; and iu France the work of overcoming a 

 pressure of one kilogramme through a space of one metre. M. 

 Dupin has proposed the application of the term dyname to this unit. 



I have gladly sheltered myself from the charge of liaving conttib.ited 

 to increase the vocabniary of scientific words by assuming the obvious 

 term 'unit of work' to represent concisely and conveniently enough 

 the idea which is attached to it, without translation." To the 

 term "unit of work," we cannot see any objection. 



Mr. Moseley's researches on the mathematical relation of machinery, 

 which he terms "the modulus," are known to our readers; in the 

 present work he has applied himself to the determination of the 

 modulus of toothed wheels, and of bevil wheels, and he has also con- 

 sidered the influence of the friction of the teeth of wheels and that 

 of their axes and weights. Upon this lie observes, "an approximate 

 form of this modulus applies to any shape of the teeth under which 

 they may be made to work correctly; and when in this approximate 

 form of the modulus the terms which represent the influence of the 

 friction of the axis and the weight of the wheel are neglected, it re- 

 solves itself into a well known theorem of M. Poncelet, reproduced 

 by M. Navier and the Rev. Dr. Whewell. In respect to wheels 

 having epicycloidal and involute teeth, the modulus assumes a 

 character of mathematical exactitude and precision, and at once es- 

 tablishes the conclusion (so often disputed) that the loss of power is 

 greater before the teelh pass the line of centres than at corresj,onding 

 points afterwards ; that the contact should, nevertheless, in all cases 

 take place partly before and partly after the line of centres has been 

 passed. In the case of involute teeth, the proportion in which the 

 arc of contact should thus be divided by the line of centres is deter- 

 mined by a simple formula; as also are the best dimensions of the 

 base of the involute, with a view to the most perfect economy of 

 power in the working of the wheels." In the third | art our author 

 has taken up a subject, but little treated upon in works of this nature, 

 hitherto. "The theory of machines, in which he considers the simple 

 powers and their applications, the capstan, the Chinese capstan, the 

 whinigin, the applications of the screw, the beam of the ste.mi engine, 

 the crank, double crank, crank guide, governor, carriage whe^!, Sec. 

 The fourth part is devoted mainly to construction, and in this are 

 carried out and applied Mr. Jloseley's researches on the line of re- 

 sistance as occurring in walls, foundations, buttresses, piers, &c. In 

 the discussion of the distance of the line of resistance from the ex- 

 trados of a structure, at the point where it most nearly approaches it, 

 Mr. Moseley has called it the modulus of stability, preferring this 

 measure of stability to the co-eflicient of stability used by the French 

 writers. In thi; determination of the pressure of earth upon revet- 

 ment wall, and in the theory of foundations, Mr. Moseley has introduced 

 to English students, M. Poncelet's application of Coulomb's theory. 

 Mr. Moseley's views upon the theory of the arch, are known to the 

 public, by his contributions to Hosking and Hann's " Treatise on 

 Bridges;" and in the present work he has inserted the tables of the 

 thrust of circular arches, calculated by M. Garide', from formulae 

 founded on the theory of Coulomb. In considering the strength of 

 materials, Mr. Moseley has applied a new method to the determina- 

 tion of the deflexion of a beam under given pressures, and under this 

 head as incidental to the discussion of rupture, by elongation, the 

 theory of suspension bridges has been considered. Upon this he 

 says, "This question, so coiu^dicated when reference is had to the 

 weight of tlie roadway and the weights of the sus[icndiiig rods, and 

 when the suspei.ding chains are assumed to be of uniform thickness, 

 becomes comparatively e^^y when the section of the chain is as- 

 sumed so as to vary its dimensions as to be everywhere of the same 

 strength. A suspension bridge .thus constructed is obviously that 

 wliicli, being of a given strength, can be constructed with the least 

 quantity of materials; or, which is of the greatest strength having 

 a given quantity of materi.Us used in its construction." A new class 

 of problems has also been introduced by the author, having reference 

 to the forms of girders connected by slender ribs or by open IVarne- 

 work. The subject of the strength of breaslsuicraers has also been 

 extensively investigated. There are several tables dispersed through- 

 out the vvork and in the appendix which are of_ great use both to 

 the engineer and architect. We are much gratifie<l with this work 

 indeed ; the more so, as the author has availed himself successfully of 

 the labours of tbe French mathematicians, whose superiority is not 

 merely unrivalled, but almost unknown in England. The best, there- 

 fore, that we can do at present, is to protit by their exertions, with 

 the hope that when once we enter into the field, we may, as in other 

 cases, ultimatelv take the lead where our neighbours have shown the 

 way. The work of I'rofrssor- Moseley may indeed be considered as 

 an earnest of what may be done in "applied mechanics," hitherto so 

 much neglected by us, although of such essential importance. Tnis 

 is a good beginning, but we hope to see the subject carried out in 

 practical examples, so as to be within the reach of the working uiau. 



