42ft 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[DECEMBEa, 



the total c«3t of the single width is stated to be about jEId.OOO; this sum 

 includes the metal castings for the future widening, and when the strength- 

 ening and wiilening of the whole will he completed the total cost will not 

 exceed .£25,000, which is stated to be a low price for a viaduct of 1200 ft. 

 long, and varying from 50 to 130 ft. in height. 



X description is then given of the experiments upon the deflection of a 

 trussed l)eam. Two stone piers were erected 100 ft. apart, with metal caps 

 and sockets built into them ; two beams were laid ami strapped together and 

 the struts fi.\ed, precisely as they would have been in the bridge; along each 

 side of these beams, but quite unconnected with them, posts are driven in 

 the ground, to which a horizontal beam was attached; six rods of deal, 

 carefully divided into inches and tenths, were then screwed to the outside 

 faces of the beams. The beams were, in the first instance, brought as near 

 as possible to a hori7.ont.il line, by means of a spirit level, and the zero 

 points on the rods made to correspond with a fixed line on tlie horizontal 

 bar. When the beams were loaded, and the deflection from the original 

 level took place, it was marked by the divisions on the index rods, which 

 being firmly screwed to the beams rose or fell with them, and showed the 

 quantity of deflection as marked by the line on the horizontal bar ; after 

 each load was put on the beams, it was allowed to remain au hour or two 

 before the deflection was measured, and after the load was taken ofl", the de- 

 flection was again measured at an interval of some hours to ascertain the 

 iiermanent set, before anotlier load was put on. The load made use of was 

 railwav bars ; they were distributed over the beams in various situations, and 

 in various quantities, varying from 1 to GO tons ; the results of which are 

 stated in a series of elaborate tables : and a large collection of diagrams 

 show the situation and form of the load and the space covered at each ex- 

 periment, liy examining these diagrams, the situation of the load, its 

 weight, and the deflection caused by it, will be at once seen ; the results of 

 these weights are given in the tables in feet and decimals, which will be 

 more satisfactory than the diagrams alone would be, to those who raay wish 

 to make any calculation, or to form a practical rule upon them for their own 

 guidance. 



The appendix contains the specifications for all the artificers' work, with 

 the dimensions of the several parts and the priced estimates ; — the drawings 

 accompanving the paper were executed by .Mr. Macniell's assistant, George 

 Ellis, Assoc. Inst. C. E. 



" Description of the mode adopted for sinking a IVell, at Messrs. Trnman, 

 Hanburi/, Buxton, and Co.'s Bretcery." By Robert Davison, M. Inst. C.E. 



The author commences this communication, by stating that one of the 

 principal objects of the brewers, is to obtain a constant supply of water at a 

 low temperature, for the purpose of cooling the worts, particularly during 

 the summer months. The quantity of water to be obtained from the land- 

 springs has (he says) been represented as not to be depended upon ; this 

 would probably be correct, if required, as frequently proposed, for the supply 

 of all the wants of a city, but if a well is properly sunk, there can be no 

 doubt of obtaining a supply of 80 to 100 gallons per minute. 



W'itli regard to the quantity of water obtainable from the chalk stratum, 

 the author believes it to be more precarious, for while instances occur occa- 

 sionally, where a considerable opening is found in the chalk and a plentiful 

 supply is obtained ; the cases it is believed are as frequent, where fissures 

 arc not met with and a failure ensues. 



He then proceeds to give a narrative of the facts which occurred during 

 the progress of an attempt to sink a cast-iron cylinder from the surface 

 down to the chalk, a depth of about 200 ft., intending to admit the springs 

 at the different levels, as might be considered most advisable. 



The well was commenced in the middle of a landspring well 10 ft. di- 

 ameter, and in order to avoid tlie usual inconveniences of pumping and ex- 

 cavating, Mr. Clark of Tottenham performed a large part of the work with 

 the " Miser" instead of by the usual methods of well-sinking. 



The landspring well was drained January 25, 183y, and the excavation of 

 a well 1 1 ft. diameter was commenced ; this was carried down of a clear 

 diameter of 8 ft. C in. inside the brick steiuiug, and when it had arrived at 

 the depth of 115 ft. 3 in-, the first cast-iron cylinder was lowered, and 

 others were gradually added, shutting out the springs as they were passed, 

 until April 3, when, at the depth of 135 ft., in a bed of yellow clay and 

 pebbles, the water overpowered the excavators, and after trying many me- 

 thods of continuing the excavation, the use of the "miser" was resorted 

 to, when the cylinders had gone down to 114 ft. On the Uth of May the 

 oyster bed was reached, at 103 ft. depth; and after some deliberation, it was 

 resolved to continue sinking down to the chalk. For seven da; s the men 

 were employed in "jumping" a heavy chisel bar to break througli the hard 

 rocky crust of this oyster bed ; at length between the 25th and 27tli of May 

 the cylinders suddenly sunk 5 ft. C in. ; the niisering was continued until the 

 depth of 180 ft. 10 in. was attained, and tlie cylinders were found to be 

 completely fixed. A pressure of nearly 100 tons applied hy powerful screws 

 was tried without producing anyeflfect; it was therefore determined to fill 

 all the space between tlie stcining and tlie exterior of the cylinder wiih con- 

 crete, although a portion of the steining was discovered to have given way ; 

 it was supposed that the cylinders would have been held up by the pressure 

 against the steining and tlie earth; the pump-work was therefore fixed, and 

 after a time the pumping commenced ; on the 21st October, after no more 



than the usual pumping (the water generally containing sandy sediment), it 

 was observed that the pavement round the well had given way ; the ma- 

 chinery was stopped, and immediately there occurred a rumliling noise 

 within the cylinders which lasted probably 4 or 5 minutes ; on examination, 

 it was found that the cylinders had sunk 4 inches, the main girders across 

 the top were broken, and on sounding the well it was discovered that an 

 extensive " blow " of sand had taken place, and filled the bottom of the 

 well for nearly 28 ft. ; this was cleared out by niisering, and after recom- 

 mencing pumping for some time, on the 14th December a separation of the 

 cylinders about 2J in. wide was discovereil at about 73 ft. from the surface. 

 Mr. J. llraithwaitc and >Ir. J. Simpson were consulted as to the best method 

 of proceeding ; the former was of opinion that there was such a subsidence 

 behind the cylinders, as would endanger the safety of the surrounding build- 

 ings. The latter did not take so serious a view of the matter; but he sug- 

 gested the sinking of an internal cylinder, if the original one could not be 

 forced down. 



After this examination, a portion of one of the cylinders was cut away at 

 72 ft. from the surface, where the soft part of the clay commenced, and a 

 dome was constructed with brick and cement all round the exterior of the 

 cylinder, with the intention of supporting the brick steining and strata 

 above, and also to carry oft" the water and prevent its softening the clay and 

 the concrete. 



On the 18th of ilarch, 1840, an internal cylinder of 2 ft. diameter was 

 lowered, within the original cylinder, and continued sinking until it reached 

 the chalk, into which it was driven 4 ft.; the space between the large and 

 small cylinders was then filled in with granite paving stones from 5 ft. in 

 depth, and then with smaller stones, broken bricks, &c. mixed with hydratdic 

 cement, to the depth of 25 ft., thus forming an eflfectual barrier against any 

 future " blow " of sand from the original bottom of the well. 



.\fter all was imagined to be secure and the pumping had recommenced, a 

 second separation to the extent of 4 in. was discovered in the cylinder ; the 

 gap thus formed was first filled in completely with wooden wedges, and a 

 cast-iron cap was afterwards bolted withinside. The well was then drained, 

 and 400 holes ^ in. diameter were drilled in the cylinder, immediately be- 

 neath the oyster bed, to admit the water from that level. It was ascertained 

 also by experiment, that tlie quantity of water obtained from the 2 ft. bore 

 in the chalk, was about 22 gallons per minute ; the bore was then continued 

 for a depth of 200 ft. making the total depth of the well and the bore from 

 the surface, nearly 400 ft., when a supply of water was obtained of 33 gal- 

 lons per minute ; some of the joints of the cylinders were then picked out, 

 to admit the water, and from all the sources combined, the quantity of 

 water obtained, was about 81 gallons per minute, or 135 barrels per hour; 

 that is, 55 barrels from the chalk spring and 80 barrels from the sand-spring 

 per hour. 



The cost of the well and the bore was .-£4444, to which must be added 

 the expense of a 12-horse steam-engine and pumps ^1351, making a total 

 cost of j;5795. 



Appended to the paper is the report of Mr. James Simpson, which gives a 

 very clear account of the state in which he found the well, and the remedies 

 which he suggested, for the accidents which had occurred. 



It is illustrated by two drawings, showing in detail a vertical section of 

 the well, with all the pumps and machinery, and also tlie tools used in the 

 excavation and the bore. 



" Description of a Self-aciing Signal for Railways." By Charles Berwick 

 Curtis, (of Acton,) .\ssoc. Inst. C. E. 



The object of this invention is, that notice shall be given by a marked 

 signal, both by day and night, to the trains on the railway, that they may 

 proceed with safety, and to regulate their speed. The signal being worked 

 by machinery, the policemen would not be required, as at present, to remain 

 on one spot, but could extend their sphere of inspection ; aud thus, by fixing 

 the apparatus at given intervals along the line, the passage of the trains 

 could be arranged with such precision as to render collision less frequent. 



The apparatus consists of a round signal, composed of glass, the up- 

 per third part red, aud the remainder green, descending into view from a 

 casing of three colours, such as black, green, aud red, in equal divisions: 

 upon the signal is a white plate, which projects in front of aud through a 

 slit in the casing; and in order that the signal raay be used by night as well 

 as by day, a lamp is placed immediately beneath the centre of the casing. 



On the near side of the rail, at a suitable distance, anil at a proper height 

 to be cleared by the steps of the carriages, is fixed a trigger, which is at- 

 tached to a horizontal shaft revolving on bearings, with a counterweight, and 

 these are connected by suitable shafts and levers with the signal-field. When 

 an engine passes and depresses the trigger, the signal-field is released, and 

 falls below the casing ; by this means the machinery is set in action, and in 

 a given time (which is regulated by clock-work) gradually raises the signal- 

 field up again, within the casing, indicating by the coincidence of the co- 

 loured compartments of the casing with those of the signal, the length of 

 time which has elapsed since the trigger was depressed. \A"hen the signal 

 has returned entirely into the case, the apparatus has resumed its original 

 state ready to be again acted upon. 



Several ingenious modifications of the apparatus are described ; and it is 

 stated that the signals which have been at work for a considerable period at 

 the London and Birmingham and Great Western Railways, have fully answereil 



