22 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Apnit, 



The ffovernmcnt also have equally profited hythis system, for they 

 can always enter the market upon tlie same terms, and ohtain any 

 de£free of talent they may re(i\iire without the necessit}' of traininjr 

 a corps of civil cnfi^iiieers of their own, which, for the reasons al)Ove 

 stated, would 1)6 found very difficult, and perhajis not without en- 

 tailina: the expense of numerous failures, which is tlie more unne- 

 cessarv, as they can ohtain the experience ready-made w ithout any 

 such sacrifice. Nearly all the fjrreat works and ini])rovements in 

 the public establishments have liitherto been obtained in this man- 

 ner • of whii-li the Breakwater and many others may be termed 

 excellent examples, and hy [pursuing the same system, the same 

 Jieneficial results will continue to lie produced. On the continent 

 the superiority of our free system of competition is in many cases 

 much admired, and will probably l)e introduced where circum- 

 stances render it practica))le ; and Eng-lish engineers are highly 

 esteemed and much employed on tlie continent." 



This is spoken fairly, and Sir Jolm takes care that lie shall not 

 lie understood as speaking invidiously, or as depreciating the con- 

 tinental engineers. He says — 



" In saying thus much, I wish to be distinctly understood, that I 

 should lie extremely sorry to be considered as under\aluing in the 

 smallest de^rrec the numerous able engineers in every department 

 on the continent, or the magnificent works which have been con- 

 structed by tlieni, or the excellent liooks they have written, which 

 have been productive of so much benefit to the profession of civil 

 engineering." 



In these sentiments we fully concur; we honour our continental 

 l>rethren, lint we demand for them as for ourselves the benefits of 

 ivliat we lielieve to be a better system — that of the competition of 

 civil enaincers. '\^'e advocate for tlieir interests a wider field of 

 exertion, and emancipation from the thraldom of the government 

 bureaucracy, protection for men of ability, and no false encourage- 

 ment for men of no ability. 



Ill expressing himself thus btddly. Sir John Rennie has done 

 very great service to the profession Ijy vindicating it from the in- 

 jurious and insidious designs of the government here, ^^•ho are 

 always seeking to estalilish militarj' engineers in capacities for 

 vhicii they are utterly unsuited. We wish other members of the 

 i)rofessioii of equal reputation would display the same dignity of 

 feelinirand disinterestedness, by publicly expressing their unfavour- 

 able opinion of the government assistance. We hope the fear of 

 losing some small amount of government patronage does not keep 

 them back from doing vhiit Sir Jidin Rennie has unhesitatingly 

 expressed. 



\Ve wish too they would imitate him in the jiroduction of liooks, 

 such as his. At anj'^ rate, their pecuniary means enable them to 

 imitate him in the lavish outlay he has made on drawings and en- 

 gravings. Tliey hai-e the drawings in their own offices, and if they 

 merely put them in the hands of tlie engravers, without any text, 

 the plates « ill iirove of \alue to professional students. We have 

 seen so many examples of lilieralit)- among tlie profession, that we 

 hope it will he equally displayed in contributions to engineering 

 literature. Mimey only is required, their time is not required; 

 and though they can plead they ha\e so little of tlie latter, they 

 liave lieen «ell enough rewarded to depri^'e them of such a plea in 

 tlie expenditure of money. 



We lia\e been ajit to adduce as a merit in professional works 

 that they were profusely illustrated, and we believe our readers 

 will agree with us, for such books are thereby of a more practical 

 nature. In this respect. Sir John Ronnie's volume has few to sur- 

 pass it; and it is undoubtedly one of those great works, which must 

 at once take its place in the standard library of engineering. No 

 exjiensc has been spared, we may say no care has heen spared, to 

 make tliat iiortion of the work complete which sjieaks to tlie eye, 

 illustrating the words of Horace — 



" Scyniiis iiritaiit deniissa jperaures 

 Quum quae sunt oculis subjects liclelibus" 



The eye of the practical man seizes at once the construction and 

 proportions in a drawing, while the most copious descrijition fails 

 to convey an impression so complete. Again, it is more easy for 

 tliose who wish to copy a good example to do so from a drawing 

 than from a description, and when we consider that a work of this 

 kind is to be a text-liook for hundreds of engineers, it appears 

 most desirable that it should be, as it is, really and truly useful. 



On leaving tlio presidential diair, Sir Jidin Rennie has not x-e- 

 tired from the pnldic service. He ncier could retire into obscurity, 

 but he could well have claimed exemption from further contriliu- 

 tion. That he has comideted this magnificent work gives him an 

 additional title to future fame, as it does to the gratitude of his 

 contem}ioraries for bis maintenance of the dignity of their pro- 

 fession. 



The Young Surveyor's Preceptor. By John Reid, Surveyor, 

 Parts I. and II. 



The object of this work is to explain the present system of 

 measuring and estimating builders' work ; — for this purpose the 

 author has given the plans of a first-rate building, and explains 

 how the measurements are taken, commencing with the digger, 

 and going on witli the bricklayer and carpenter. The dimensions 

 are all given in detail as taken off" in estimating, and are accom- 

 panied with a specification of each trade. Mr. Reid appears to 

 have adopted the practice of the most experienced surveyors, and 

 has produced a work which is likely to be of great benefit to the 

 jmpil, in assisting him in his professional pursuits. In saying this, 

 we must caution him not to imagine that he can obtain a sound 

 practical knowledge of the duties of a surveyor or architect, from 

 merely reading or studying this work, or any other book or 

 lecture : it can only he attained by accompanying an experienced 

 surveyor in measuring or making an estimate of the building itself. 



PROCEEDINGS OF SCIENTIFIC SOCIETIES. 



INSTITUTION OF CIVIL ENGINEERS. 



Fell. 22. — Joshua Field, Esq., President, in the Chair. 



The paper read was by Mr. A. Mitchell, of Belfast, Assoc. Inst. C.E., 

 " On Submarine Foundations ; particularly ttte Screw-pile and Moorings." 



Considering that the entire subject of tlie various sorts of piling, of solid 

 stone foundations, of cofferdams, of masses of concrete, and the numerous 

 modes adopted hy ingenious men for overcoming local difficulties, would 

 occupy too much time, and scarcely possess novelty, the author restricted 

 himself alrao&t entirely to ihe description of the works executed by him with 

 the screw-pile, as that had been chiefly employed for supporting structures 

 on loose sand or mud banks, wholly or partially covered by the sea, where it 

 had been previously considered very hazardous, if not impracticable, to erect 

 any permanent edilice ; and in his narrative, he scrupulously avoided all 

 comparison with other modes of proceeding, even when they had the same 

 object. The origin of the screw-pile was the screw-mooring, which was de- 

 signed for the purpose of obtaining, for an especial purpose, a greater hold- 

 ing power than was possessed hy either the ordinary pile or any of the usual 

 mooring-anchors or blocks, of however large dimensions. It was proved by 

 experiment, that if a screw, with a broad spiral flange, were fixed upon a 

 spindle, and forcibly propelled by rotary motion to a certain depth into the 

 ground, an enormous force would be required to extract it by direct tension; 

 and that the power employed must be sufticient to drag up a mass of earth 

 of the form of the frustruni of a cone reversed — the base being at the surface 

 of the ground, and the section of the apex being equal to the diameter of 

 the screw. The extent of the resisting mass must, of course, depend upon 

 the natural tenacity of the soil. Even in this reasoning, it must be evident 

 that a vertical force was calculated upon ; but as, practically, that seldom if 

 ever occurred, the angle of tension and the curve of the buoy-cable again 

 gave the moorings greater power. This was found to be correct in practice, 

 and the application of the moo.rings became very extensive. An arrange- 

 ment was made with the port of Newcastle-on-Tyne, by which, for the sum 

 of 2,500/., the right of fixing these moorings in the Tyne was given ; and 

 Mr. Brookes, the engineer, showed that last year, whilst in the neighbouring 

 port, damage was done to the shipping to the extent of nearly 30,000^, no 

 injury was sustained in the Tyne, entirely owing to the sound holding of 

 Mitchell's screw-pile mooring?. It naturally occurred to Mr. Mitchell, that 

 the same means of resistance to downward pressure might be used ; and he 

 proposed to apply it for the foundations of lighthouses, beacons, and other 

 structures, which, for maritime purposes, it might be desirable to place upon 

 sand and mud banks, where hitherto it had been considered impracticable to 

 place any permanent edifice. In the year 1838, a plan for a structure of this 

 nature for a lighthouse, on the Maplin Sand, at the mouth of the Thames, 

 was laid before the corporation of the Trinity House, supported by the 

 opinion of James Walker, Esq., their engineer. The nine iron piles, 5 inches 

 diameter, with screws 4 feet diameter, were accordingly driven 22 feet deep 

 into the mud, and, with proper precaution, they were allowed to stand for 

 two years before any edifice was placed upon theiu. The lighthouse was 

 subsequently constructed, and, as was festilied by Mr. Walker, had stood per- 

 fectly until the present time. Pending Ibis probation, it was determined to 

 erect a lighthouse to point out the entrance to the harbour of Fleetwood-on- 

 Wyre, and under the advice of Captain Denham, R.N., the screw-piles were 

 adopted. The spot fixed on was the point of a bank of loose sand, about 

 two miles from the shore ; seven iron piles, with screws of 3 feet diameter, 

 were forced about 16 feet into the bank, and upon them timber supports 48 

 feet in vertical height were fixed to cany the house and lanthorn. This 

 structure was completed in six months, and was perfectly successful, never 

 having required any repairs to the present time. A similar lighthouse was 

 erected near Belfast ; and since then several others, with a great number of 

 beacons, have been fixed in situations heretofore deemed impracticable. 



