352 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[October, 



to overflow. It would appear that as the number of wells and bore-holes 

 had increased in some districts, the water levels had been depressed ; in 

 several cases, the cause of this had been traced to wells which had been 

 bored at extremely low levels, and in others to the increased pumping. 



Messrs. Worsencroft and Brothwood, of Hammersmith, who practised 

 well-sinking extensively some years since, were most succcessful in wells 

 where their competitors had ceased working when they had pierced some 

 distance into the sand strata, whence the water only rose to some distance 

 beneath the surface ; but by continuing the boring down into the chalk, they 

 obtained overflowing wells. 



Mr. Scanlan said that the difference between the water from the two 

 strata was easily discovered by analysis : the water from the sand contained 

 common salt and no lime, while that from the chalk contained lime and no 

 common salt. 



Mr. Clutterbuck said, in answer to Mr. Simpson's objection as to the 

 identity of the chalk and sand water levels, the disparity of level that he 

 spoke of, occurred in localities where there was an exhaustion by over-flowing 

 Artesian fountains, in which case a discharge of water was created below its 

 natural level, which would cause the same kind of depression either in the 

 sand or the chalk, as that which was caused by pumping the same quantity 

 of water from a corresponding level where the water would not flow above 

 the surface ; the only difference being, that in the former the depression was 

 permanent, and in the latter it was coincident with the temporary exhaustion 

 of the pumps. As the water was discharged from the Artesian fountains 

 more rapidly than it rose through the sand from the chalk, a permanent de- 

 pression took place in the wells sunk into the sand, whilst a lesser depression 

 occurred in the chalk, and thus caused a disparity of level. Thus the water 

 level, hi the wells sunk into the sand in London, was temporarily depressed 

 by pumping from others in the neighbourhood, and the level was regained 

 when the pumping ceased. 



Mr. Braithwaite eulogized the industry and observation of Mr. Clutter- 

 beck, and he hoped that he would extend his investigations to the point of 

 the outcrop of the basin of the river Thames, which he had stated to be 

 near Woolwich. He must, however, dissent from the author's views as to the 

 supply of water to the sand under the plastic clay, being derived from the 

 chalk, and also, that if no rain fell during a period of three years, the water 

 in the wells referred to in the section, would retain their relative levels, at 

 an inclination of not less than 10 ft. in a mile. He believed that any con- 

 tinuation of dry weather, which would affect the land springs, would also 

 diminish the filtration, and the upper part of the basin on all sides would be 

 affected before the greater depths. He also differed from Mr. Simpson as to 

 the supply for the overflowing wells at Kingston, Mitcham, and other parts, 

 being from the chalk ; on the contrary, he was of opinion that it proceeded 

 from the sand under the plastic clay, and he instanced Mr. Palmer's well at 

 Kingston, and that sunk by Mr. Clark at the Kingston Union. The latter 

 well was within 100 yards from the former: it was 420 ft. deep to the sand 

 spring, and the water rose to within 7 ft. from the surface. While the water 

 stood at this level in the well at the Union, it overflowed at Mr. Palmer's ; 

 but when the level at the Union was reduced by pumping to 20 ft. from the 

 surface, the water at Mr. Palmer's well ceased to overflow: thus, he con- 

 tended, establishing the fact that the water in both wells was derived from 

 the sand, and not from the chalk. 



Mr. Clutterbuck observed that the reason why there was a depression ob- 

 servable at Kilburn, and not at Cricklewood, was easily explained, if the de- 

 pression caused by pumping in London was laid down on a diagram. In the 

 centre of London the depression amounted to 50 ft. below Trinity high- 

 water mark ; at the Hampstead Road, to 38 ft. ; and at the Zoological Gar- 

 dens, to 25 ft. This line, if produced, would show a depression below the 

 natural water level at Kilburn, and fall into the non-depressed level about 

 Cricklewood. Though it was impossible to prove the assertion, that the 

 water level in the chalk would never assume a less inclination than 10 ft. in 

 the mile, he was led to the supposition by observing that the level ceased to 

 decline when it became depressed to that extent ; and many wells at a dis- 

 tance from the vent, which at the time of such depression cointained only 

 3 ft. of water, were never known to become dry. 



Mr. Clark stated that he had found the water rise from the chalk to very 

 different levels in the various wells and bore-holes which he had sunk, and 

 be had not observed that the supply of water was affected so immediately 

 after rain as had been described by Mr. Clutterbuck. He presented a paper 

 containing memoranda relative to wells sunk and bored for a considerable dis- 

 tance on both sides of the river Thames. This document gave the depths at 

 which the chalk was arrived at and the water was found, and the height at 

 which it stood in several wells round London. It stated also, that in 

 London the average depth to the chalk was 220 ft. ; that the water generally 

 rose to within 70 ft. of the surface, but that near the river it rose to within 

 50 ft. In some particular cases, such as the Lunatic Asylum at Wandsworth, 

 the depth to the chalk was 323 ft., yet the water rose to within 30 ft. of the 

 surface. 



Mr. Davison presented a copy of a drawing made in the year 1822, show- 

 ing the depth of sinking and of boring, and the height to which the water 

 rose, in ten of the principal wells in London at that period, which it was 

 remarkable was exactly Trinity high-water mark. It appeared also that the 



water did not now rise in the same wells to within 50 ft. of that point, 

 showing a depression of nearly 2 ft. per annum. ' 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



Thirteenth Meeting, 1S43.— Hehl at Cork. 



;From the Jthenaum.) 



(Continued from page 324.J 



Tidal Observations on the Firth of Forth, and of the East 

 Coast of Scotland. 



Mr. Scott Russell read the concluding " Report of a series of Observations 

 on the Tides of the Firth of Forth and of the East Coast of Scotland," 

 noticed in last month's Journal. 



These observations extended over several seasons, and no complete report 

 had been hitherto presented, as the observations of each former season had 

 only shown the necessity of further extending the observations. The obser- 

 vations of the first season had proved the existence of certain anomalous 

 tides, which had not formerly been accurately examined, and proved that 

 these anomalies were more extensive than was at first conceived. Next 

 season the observations were more widely extended, so as to comprise the 

 whole phenomena, including many adjacent places, to which the same ano- 

 malies were traced ; and thus the general nature and extent of the pheno- 

 mena were determined with accuracy and precision, and reported to the last 

 meeting. But it was found that great differences of opinion existed with 

 reference to the cause of these ascertained phenomena, and rendered it ob- 

 vious that the observations required to be extended still further, in time and 

 extent, in order to settle conclusively the questions which had arisen out of 

 the former inquiries. But this last series, from their extent and complete- 

 ness, had now been so fully examined and discussed, as to afford ample 

 means of deciding on the nature of the phenomena, and determining their 

 origin. Simultaneous observations had been luade at nearly twenty stations 

 on the east of Scotland, from Newcastle and Shields to Inverness, and as 

 many as 2000 observations a-day registered and discussed. The results of 

 these were exhibited in the tables and diagrams accompanying the report : 

 and the result of the whole had been to elucidate, in a remarkable manner, 

 the mechanism which propagates along our shores and rivers the great ocean 

 wave, which carries from one place to another the successive phenomena of 

 the tides — in such a manner as could not have been attained by any system 

 of observation less extensive than that which had been adopted. It is pretty 

 generally known that the phenomena of the tides with reference to their 

 generating cause, the influence of the mass of the sun and of the moon in 

 the various relations of distance and direction of these luminaries, have re- 

 cently been examined with great success, in a series of researches carried 

 on. first by Mr. Lubbock and then by Mr. Whcwell, partly with the co-ope- 

 ration of this society. By means of their labours we are now enabled to 

 predict, with unlooked-for accuracy, the time of high water, and the height 

 of the tide in many of the harbours of Great Britain. But many of the 

 local phenomena of tides remained unaccounted for, and these had been the 

 object of a special series of researches, of which the present formed a part ; 

 the object being to determine in what way the conformation of the shores, 

 and of the bottom of the sea, and the forms of the channels of rivers and 

 friths, affect the phenomena of the tidal wave. The rivers Dee and Clyde 

 had been formerly examined with this view. To these were now added the 

 Forth, the Tay, and the Tyne, and the northern shores of the German Ocean. 

 The manner in which these observations were conducted, is not the usual 

 one, of noting down simply the hour at which high water occurs, and then 

 the hour of low water, along with the height at which the water stands at 

 these times. Such a method had been found quite inadequate to the pur- 

 poses for which such observations are required, and, indeed, he thought it 

 of importance that all tide observations should, if possible, be made in the 

 manner he was now about to describe, especially all tide observations made 

 for scientific purposes. This plan was, to carry on simultaneously at the 

 places examined, a series of continuous observations, every five minutes night 

 and day, by successive observers, without intermission, for the period of a 

 month, or of several months, as might be required. Printed forms were 

 sent to all the stations, and in them, the observers simply noted down every 

 five minutes, the height of the tide on a graduated scale placed before him. 



1 In a letter to the Secretary of the Institution, dated April 28, 1843, 

 Dr. Buckland says, " I think that Mr. Clutterbuck has added many new facts 

 in confirmation of the theory he maintained last year, as deduced from his 

 observations previous that time. He has also, I think, found a satisfactory 

 solution of the apparent anomaly afforded by the well at Epping. I consider 

 the series of observations he has been making near Watford, to be very im- 

 portant as throwing light on the movement of the subterraneous sheets of 

 water which supply springs and rivers. I believe these observations to be 

 correct, as I know that he has been indefatigable in collecting facts, and I 

 consider them calculated to illustrate a problem of high interest to civil en- 

 gineers as well as to geologists." 



