1850.J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



183 



Among the experiments in Portsmoutli Dockyard we find a series 

 for determining the deflection of bars, subjected to the "sudden 

 application of weight without impact;" and another series for deter- 

 mining "the effects of a camber or upward convexity of the beam." 

 Both these series, though tlie fact is not alluded to in the Report, 

 were suggested in this Journal, by the paper above referred to, in 

 the sections discussing the effects of instantaneous loading and the 

 effects of centrifugal force: the experimental results amply confirm 

 the conclusions arrived at in the paper. 



The whole question of the dynamical deflection of girders must 

 now be considered as set at rest. It is quite obvious that a 

 thousand circumstances occur in practice which would vitiate all 

 theoretical conclusions as to the very minute quantity which the 

 excess of dynamical over statical deflection is shown to be. A 

 very slight original curvature of the beam, its imperfect elasticity, 

 a bad joint of the rails, the pulse of the engine even, would set all 

 mathematics at defiance. However, a great service has been 

 rendered by the investigation; the value of the result is in nowise 

 diminished because it "shows the eftects of velocity to be incon- 

 siderable. Next to security, the most important requirement of 

 raihvay travelling is a conviction of security. It is the reasonable- 

 ness of such a conviction, long ago demonstrated in these pages, 

 which the admirable labours of I'rofessors Stokes and Willis, 

 Captain James and Lieutenant Galton, have elucidated by means 

 of experimental induction. 



SUPPLY OF WATER TO THE METROPOLIS. 



On the means of Supplying the Metropolis with Pure Water and in 

 am])le quantity. By Mr. Joun Pvm. — (Paper read at the Society 

 of Arts.) 



The author commenced by stating that the water supply of the 

 metropolis is derived from three sources: — the New River, the 

 Thames, and the Lea; wells sunk to different depths in the London 

 clay, sand, and gravel; and Artesian wells. Of the water thus 

 obtained, that from the Thames is impure, that of the New River 

 almost as bad for a great part of the year, whilst many of the wells, 

 being impregnated by drainage from burial-grounds or sewers, 

 yield water of a decidedly pernicious quality. Artesian wells, 

 that is, wells sunk through the London clay into the chalk, produce 

 excellent water; but only of limited quantity, the supply failing 

 in dry w eather, and being seriously affected if a deeper well be sunk 

 in the neighbourhood: indeed, it appears certain, that if all the 

 water lying in the chalk of the London basin could be brought 

 to the surface, it would fall short in quantity of that required. 

 The question which the author proposes is, how to obtain a suffi- 

 cient supply through the medium of these wells; and his plan is 

 as follows: — At a given distance from the Thames, on each side 

 thereof, to sink down to the chalk a series of shafts, and form 

 a short canal from the mouth of each shaft to the bank of the 

 river, at such a level that when the tide is at a given height, the 

 water will flow into the shafts; whereby an immense supply would, 

 twice a day, be given to the chalk basin. Other shafts are to be 

 sunk at small distances from the former ones, up which the filtered 

 water would rise, as into inverted syphons, till near the level 

 of the Thames; and from these ascending-shafts it should be dis- 

 tributed by steam-power. By this plan, the chalk stratum of the 

 London Basin, extending from Highgate to Forest Hill, would be 

 converted into a large filter. A shaft of the diameter of those 

 of the Thames Tunnel would probably filter a quantity of water 

 equal to that supplied by the New River. The shafts might be con- 

 verted into preparatory filter-beds by filling them with sand and 

 gravel. The author considers that the water being thus quickly 

 filtered through the chalk, would not become so impregnated with 

 lime as the water usually got from Artesian wells, which has lain 

 in it for a length of time. This plan would allow of the existing 

 mains, pipes, &c., of the water companies being used as before. 



The author stated, as an example of the absorbing properties of 

 the chalk, that farmers, on or near the outcrop of the chalk, 

 frequently sunk shallow wells, which served as drains and removed 

 a large portion of useless surface water. 



It was stated that the water from the Artesian wells contains 

 three times the amount of chemical impurities of any of the waters 

 from the streams around London: the water of the Lea contains 

 twelve grains of lime to the gallon; but the water from Artesian 

 wells, in addition to lime, contains sulphate and muriate of soda, &c. 



THE BARROW MONUMENT, ULVERSTON. 



This interesting testimonial to the late Sib John Barrow has 

 just been commenced in the immediate neighbourhood of his birth- 

 place — Dragley Beck, near Ulverston. A public subscription was 

 raised for the purpose, amounting to upwards of 1000/., and the 

 whole is erected under the auspices of the Board of Admiralty. 

 The type of the memorial, as will be seen in the elevation and sec- 

 tion given in our next page, is to be found in the well-known Eddy- 

 stone Lighthouse, and, like that stately beacon, it will be a highly 

 serviceable sea-mark in the difficult and dangerous navigation of 

 Morecambe Bay. The i)lan of the building i« circular, about 4-5 ft. 

 diameter at the base, and tapering gracefully to a lantern, 12 feet 

 diameter, and finished by a dome. The extreme height is 100 feet. 

 For the substantial walling the material used is known as "Trap" 

 stone; the facings, &c. of Birkrigg limestone. A seat will encircle 

 the foot of the tower at the exterior, and the various levels of the 

 interior will be reached by a geometrical staircase. The highest 

 room is intended for an observatory, and will be so constructed 

 that it may at anv time be easily converted into a lighthouse. 

 The first stone was'laid on the 15th inst. by Sir George Barrow (of 

 the Admiralty), assisted by his brother, Mr. John Barrow, in the 

 presence of a vast concourse of spectators. The design and super- 

 intendence are committed to Mr. Andrew Trimen, architect, of the 

 Adelphi; and the contractors are Messrs. Smith and Appleford, 

 also of London. 



Plan A. 



From the elevated position of the monument it will be con- 

 spicuous on all sides for a considerable distance. It has been 

 ascertained that an unobstructed view of one of the finest bays in 

 Europe, the Bay of Morecambe, from Green Odd round to the 

 entrance of the Duddon, will be gained from the observatory of 

 the Tower, with the exception of only about 1200 yards, which 

 will be obscured by the highest point of Birkrigg. It also over- 

 looks the Isle of Man, and the coast of Wales from Liverpool to 

 Anglesea. 



The ceremony was attended by every token of rejoicing; and 

 a sumptuous dinner closed the festivities of the occasion. 



