1X2 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[January, 



The grc.-.tcr degree ol atlcimation in which tiie steam was fomirl on llie com- 

 pletion of the stroke in one engine than in another, compared with the pres- 

 sure of the resistance, and with the amount of expansion determined by the 

 period of closing tlie valve, alone proved that the ordinary theory was inade- 

 quate to explain the action of steam in these engines. 



He had for some time conjectured that a hidden and unsuspected cause in- 

 fluenced the performance of the Cornish cnijine : and if he had not been suc- 

 cessful in discovering its nature, he considered the analysis as placing the 

 fact beyond question, tbiit the (juaiitity of action resulting from the steam 

 admitted into the cylinder wns much below the force of the resistance op- 

 posed to it, and overcome. 



June 23.^The Prksident in the Chair. 



John Frederick Bateman was balloted for and elected a member. 



" On the Stamping Emjines in Cornwall." l!y John Samuel Enys, A. Inst. 

 C. E. 



The process of stamping or reducing the ores of tin in Cornwall, by means 

 of iron stamp-beads, which crush the ore in falling upon it. was formerly 

 effected in mills worked by water power. 'I'hese have been, from economical 

 and other reasons, for the most part superseded by the use of steam ; and 

 even with inferior engines, the result has been such as to enable the poorer 

 portions of the lode (which were frequently left in the mine) to be now ad- 

 vantageously worked. 



The work performed by the stamjiing engines was reported with that of 

 the pumping engines, and showeil the duty to be from 1 6 to 25 million tb. 

 raised one foot liigh by one bushel of coal, as estimated from the actual 

 ■wciglit of the stamp-heads. The engines appropriated for this purpose were 

 generally old double-acting engines of inferior character, and not uufrequently 

 in a bad state of repair. The use of expansive steam was tried with good 

 effect upon them, and induced Mr. James Sims to build an engine calcu- 

 lated more fully to develop the advantages of this principle. He accordingly, 

 in the year 1835, erected one at the Charlestowii mines. It was a single- 

 acting engine, communicating the movement direct to the cam shaft for 

 lifting the stampers witlioiit the intervention of wheel-work. The first 

 reported duty, iu December, 18.35, was 43 millions, which was two-fifths 

 more than bad jireviously been performed by stam))ing engines. Siil)se- 

 quently, Mr. Sims erected other engifles of similar constniction, and from 

 them may be taken the reported duty in .'Vpril, 1840 : — 



Charlestoyra Mines . . 59,589,884 lb. 



Carn Brae . . . 57,611,073 



Wheal Ketley . . . 58,748,452 



T'lis increased duty induced other engineers to turn their attention to the 

 subject, and they have constructed engines which equal these duties ; the 

 chief variation being the adoption of double action, which seems generally to 

 be preferred. 



This paper is accompanied by four drawings of the Carn Brae stamping 

 engine, by Mr. Sims, junior, showing in great detail the construction of the 

 engine and the stamping machinery. 



" On the Effects of the Worm on Kyauized Timber exposed to the action 

 tf Sea U'ater, and on the use of Greenheart Timber from Demerara, in the 

 same situations." By J. B. Hartley, M. Inst. C.E. 



There are probably few ports in England where the inconvenience resulting 

 from the attacks of n>arine worms ( 'Teredo naralisj on the timber of tlie 

 (lock gates and other works exposed to their action, is more severely felt 

 than at Liver])Ool. The river Mersey has a vertical rise of tide of 27 feet at 

 spring, and 13 feet at neap tides, and the stream being densely charged with 

 sht, a considcr.ible deposit takes place in the open basins, and to some 

 extent in the docks. Tiie latter are cleansed by means of a dredging ma- 

 chine, but the former are usually "scuttled," for which purpose sewers con- 

 nected with the docks surround the liasins, having several openings furnished 

 with " clows," or paddles, so that the rush of water from the docks may be 

 applied for clearing away the mud from any particular part of the basin. The 

 security of these paddles is, therefore, of the greatest importance, as the 

 failure of one of them might, by allowing a dock to be suddenly emptied, 

 •cause great damage to the shipping. These paddles have been usually con- 

 structed of English oak or elm, and being much exposed, they suffer from the 

 attacks of the worms. Cast iron paddles have been tried ; liut in conse- 

 quence of the rapidity of the corrosive action, they soon became leaky, and 

 were abandoned. Kyanizcd oak timlier has been tried on the back of these 

 paddles, and found to l)e perforated by the worm in the same time as unpre- 

 pared wood. Some oak planks, two inches and a half thick, Kyanized at the 

 Company's yard, were used on the west entrance gates of the Clarence Half- 

 tide Basin, and in 14 months were completely destroyed. Several similar 

 instances of the non-etticiency of the Kyanized timber are given ; and the 

 antlior proceeds to designate the timber which resists best in such situations. 

 He considers that teak is less liable to injm-y than English woods, and in- 

 stances the inner gates of the Clarence dock, which have been built for 10 

 years, and at present are but slightly attacked. 



The timber which he prefers for dock works is the Greenheart. It is im- 

 imrtcd from Demerara, in logs of 12 to 16 inches square by '_5 to 40 feet 

 long, and costs about seven shillings per cubic foot. Of its power to resist 

 the attacks of worms, he gives many proofs : o[ie of them may be cited. At 

 the first construction of the Brunswick Half-tide basin, several elm clows 

 were placed at the west entrance ; these were destroyed by the worms in two 



years, and were replaced by others made of greenheart : the joints of the 

 jilimk being toiigued with deal, to render them completely water-tight. 

 These clows have now been down about seven years, and, altliough the deal 

 tongueing has been destroyed by the worms, the greenheart planking remains 

 untouched and perfectly sound. 



Many methods of protecting commou timber h.ivc been tried : but the only 

 successful ones adduced are — 1st. the use of broad-headed m.etallic nails 

 driven nearly close to each other into the heads and heels of the gates, but 

 if driven an inch apart, the worm penetrates between them : and 2ndlv, 

 steeping the timber in a strong solution of sulphite of copper from the Parvs 

 copjier mines in .\nglcsea. Some paddles made of English elm thus pr'e- 

 jiared had been in use upwards of three years, anil, on an examiiiation, were 

 found to be very slightly injured ; while the unprepared timber about them 

 was quite destroyed. 



The author observes, that the outer gates of the wet basins are most in- 

 jured by the worm, from the sills being low down, and the ciiange of water 

 every tide assisting the growtli of the worm. Those parts of the gates which 

 are alternately wet and dry arc more injured by the worm than the parts 

 immersed always iu the same dc))th of water. .\t the spot where a leak 

 occurs from a bad joint, a defect in the caulking, or other cause, the woriu 

 commences its attack ; so that the most incessant attention is required. 

 Those basins into which the sewers of the town discharge themselves are 

 coi;i|)arati\ely free from the worm, from whijh it would appear that sidphu- 

 retied hydrogen gas acts in some measure as a protection against the attacks 

 of the worm. 



" .'tn orcount of the actual state of the Works at the Thames Tunnel (June 

 23, 1840;." By .M. I. Brunei, M. Inst. C. E. 



In conse(|uence of local opposition, the works have not advanced much 

 since the month of March, 1840 ; but, as that has been overcome, and facili- 

 ties granted by the city, the works will be speedily resumed, ami the shaft 

 ou the north bank commenced. 



The progress of the Timnel in the last year has been, within one foot, 

 equal to that made in the three preceding years. During those periods col- 

 lectively, the extent of the Tunnel excavated was 250 ft. 6 in., and during 

 the last year the excav.ition has been 249 ft. 6 in. This progress has been 

 made in spite of the difliculties caused by the frequent depressions of the 

 bed of the river. These have been so extensive, that in the course of 28 

 hneal feet of Tunnel, the quantity of ground thrown upon tlie bed of the 

 river, to make tqi for the displacement, in the deepest part of the stream, has 

 been ten times that of the excavation, although the space of the excavatioa 

 itself is completely replaced by the brick structure. On one occasion the 

 ground subsided, in the course of a few minutes, to the extent of 13 feet in 

 depth over an area of 30 feet in diameter, without causing any increased 

 inliux of water to the works of the Tunnel. The residts now recorded con- 

 firm Mr. Bnmel in his opinion of the efficiency of his original plan, which is 

 " to press equally against the ground all over the area of the face, whatever 

 may be the nature of the ground tiirough which the excavation is being 

 carried." The sides and top are naturally protected ; but the face depends 

 wholly for support upon the poling boards and screws. The displacement of 

 one board by the pressure of the ground might be attended with disastrous 

 consequences ; no deviation therefore from the safe jilan should be permitted. 



The paper is accom])anied tiy a plan, showing the progress made at diffe- 

 rent periods. It is stated that a full and comph'te record of all the occur- 

 rences which have taken place during the progress has been kept, so as to 

 supply information to enalde others to avert many of the difficulties encoun- 

 tered by Mr. Brunei in this bold yet successful undertaking. 



June 30. — Henrv Robinsox Palmer, V. P., in the Chair. 



" Description of an Instrument for describing the Profile of Roads." By 

 Henry Chapman, G. Inst. C. E. 



The object of the author in the invention of this instrument was to facUi- 

 tate the mode of making a preliminary survey for railways by a machine of 

 a simi)le construction, and composed of very few moving parts. It may be 

 thus briefly described : — 



A light frasie with springs and upon four wheels carries the machinery, to 

 which a rotary movement is communicated from one of the wheels, which is 

 keyed fast upon its axle. A double-threaded screw and a series of wheels 

 work give motion to a cylinder, upon which a length of paper is coiled ; tbi- 

 cylinder revolves, and moves simultaneously in the direction of its axis. A 

 pencil, which moves parallel to the axis of the cyUmler, marks a line upon it, 

 with a velocity varjing according to the inclination of the road, and is so 

 arranged, that when tlie machine is passing along a level, the motion of the 

 pencil will equal that of the cylinder. In ascending inclitied planes, it will 

 be retarded, and in descending it will be accelerated. By these means a 

 rising or falling line will be accurately drawn. This variation in the action 

 of the })encil is accomplished by means of a friction-wheel working against 

 a cone, the different diameters of which regulate and determine the speed. 

 The position of the friction-w heel upon tlie cone is determined by the change 

 of iHisition of a jiendulum vibrating witliin a case which is filled with a dense 

 fluid, for the purjwse of rendering its action more uniform. 



The machine will trace a section of a road iu lengths of five miles upon 

 each sheet of paper, to a horizontal scale of 20 chains per mile, and to a ver- 

 tical scale of 200 feet to an inch. That no inconvenience may be felt from 

 the smallness of the scale, the mstrument is furnished with scales with sliding 

 verniers, from which memoranda can be niivde of the distance nm, and of the 



