1840.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



383 



not often occur ; and as practice and experience are the best test of value, he 

 has felt !i good deal of difficulty in dealing with it. He has mide it a matter 

 of inquiry, and having had a great deal to do with wharf property, perhaps 

 more than most professional persons he has endeavoured to bring the ex- 

 perience he possesses and the infi rmation he could gain to bear upon the 

 subject ; the conviction of his mind is, that 2d. a superficial foot, which was 

 talked of. the property could not bear -, he thinks it would be excessive ; but 

 he thinks Id. a foot superficial might be borne, which would yield nearly 

 2,500i. per annum upon the siilid embankment ; he thinks so, as he has already 

 Stated, from the experience he has, from the advantages it is calculated to 

 afford. It involves the improvement of the navigation of the river, which 

 the persons using the wharfs would be benefited by; it gives them an in- 

 creased quantity of freehold property; and with regard to tliat freehold pro- 

 perty, if, as was done in a fomier case, he believes, and that to some con- 

 siderable extent, at the time of building Blackfriars Bridge, tlie freehold 

 property was madi^ also free from rates and taxes, it would atford another 

 advantage. That properly so reclaimed at Blackfriars Bridge was charged 

 at Ifi. a foot, he finds ; as far as he has been able to learn, it was found to work 

 well ; and one advantage that would be afibrded here is, that in some cases 

 persons with bad wharf walls would get good ones. In other cases, the gene- 

 ral property would be secured by this embankment, and a great public high- 

 way, the Thames, would be benefited, and persons using it. Persons possess- 

 ing themselves of freehold land, he thinKS. would have no just ground of 

 complaint in paying \d. a foot for the property reclaimed ; but tljere would 

 be this difficulty about It. and one which the honourable Committee will feel 

 perhaps to be considerable, a penny a foot on some portion of the property 

 would be much ton little, and on others it would be too much ; in some cases 

 persons would get Ihe more valuable part of the property in Thames-street; 

 he knows that they would be very glad to pay 2d. a foot ; but in other cases 

 he knows persons w ould not be willing to pay a penny per foot. The hon- 

 ourable member for Lambeth has alluded to eases in which the advantages 

 now possessed by individuals would be lessened. Those points all want con- 

 sideration. Every individual case, to do what he is quite sure the Committee 

 are desirous to do, viz. to do justice, would require a matter of consideration ; 

 that is an affair which he has not entered upon except in this way, he has 

 judged from bis own experience. He has valued a good deal of wharf pro- 

 perty ; he has lately had to buy a good deal for the Crown at the enormous 

 price that was invariably asked ; we were then told that a few feet « ere worth 

 nobody knows what money. He has also bad to value with reference to a 

 good deal of the parish assessments along the river, Hungerford Market and 

 other parts; now he is quite satisfied that in some cases it would be an ex- 

 traordinary boon at a penny per foot ; but in others \d. per foot could not be 

 borne. How the separate cases are to be met he must leave to the Committee ; 

 but, in going from wharf to wharf, (he does not mean the C^ommittee to un- 

 derstand that he has been on every wharf, he has been on many), he has put 

 down what each h harf would bear, and that comes nearly to Irf. per foot, so 

 that he feels warranted in saying that 2.500/. a year might be charged for the 

 whole line of embankment, from one extremity to the other, where a solid 

 embankment exists ; but it is a miilter of considerable difficulty. He has en- 

 deavoured to do it as honestly and impartially as he could, and bring all the 

 experience which he has to the subject. Then as regards the dwarf piling, 

 that is 72.5,700 feet ; the superficial quantity enclosed by the dwarf piling, a 

 halfpenny per foot has been talked of for that ; he has more difficulty in this 

 than in the other case, in saying what is right. There are advantages with 

 reference to the navigation and security oi buildings, and the possession of 

 freehold instead ol^ what, so far as he has heard of the evidence, appears to be 

 a doubtful property, the city claiming a right over it, which would be aban- 

 doned, he takes it. in this case. But he has not, as in the case oF Blackfriars 

 Bridge, any test here, and after thinking of it a good deal, he has taken an 

 annual sum for it of 1,133/., that is, between a halfpenny and a farthing, the 

 intermediate sum, as an annual sum ; a halfpenny per foot was mentioned ; 

 he thought it too much, for it gave larger rent in some phicesthan it appeared 

 to me they could bear, though they have advantages in this case ; by becom- 

 ing their own freehold they would have a right to embank at any future 

 period ; but it is a matter of so much difiicully, that to give his evidence as 

 he could upon some subjects, to say that he knows from experience that the 

 property would produce such results, he could not pretend to do. It is open 

 to much doubt. His impression is, that in both cases he has been moderate ; 

 he intended to be so. It would be worth to sell, twenty-five years' purchase. 

 He would not be warranted in putting it at 25 years' purchase unless it was 

 connected with the other portions of tbe properly. Freehold land connected 

 with buildings is generally at 20 years' purchase only. A ground-rent, amply 

 secured, has sold tor 30 or 31 years' purchase. This is an intermediate case 

 of 25 years' purchase. He thinks 30 years would be too much, as there is 

 some speculation in it, or else it is a ground-rent, and therefore he thought 

 25 was safer. 



The following is tbe Report of Mr. Walker made in 1821. referred to in his 

 evidence given in the last month's Journal. 



•■ From the recent, and, we believe, accurate surveys that have been made, 

 it appears that the difference of level in the water above and beluw' bridge, 

 towards the latter end of the ebb of a spring tide, is from 4 feet 4 inches to 5 

 feet 7 inches ; the water is therefore at present dammed up to that extent at 

 the bridge ; we find, by calculation, that this pen will be redticed from, .say 5 

 feet, to about 3 inches, by the proposed alterations ; and the water above 

 bridge, at low water, will therefore be 4 feet 9 inches lower than at present. 

 But as the velocity of the stream above bridge will be increased by a greater 

 quantity of water having to run through in the same time, both on-account 

 of the water flow ing higher at high water, and ebbing lower at low water, the 

 inclination of the surface will also be increased ; and this lowering of 4 feet 

 9 inches, above referred to, will decrease as the distance from the bridge in- 

 creases. Now, by the survey above referred to, the present rise in the sur- 

 face of the water from London Bridge to Westminster Bridjje, at low water, 

 is 12 inches, being 6 inches, per mile ; and supposing the velocity, after the 

 alterations, to be increased so as to produce twice the inclination, or 12 inches 

 per mile, the surface of the water at Westminster Bridge will be lowered, at 



low water, 4 feet 9 inches, less one foot (the increase of fall), or 3 feet 9 inches 

 below its present level at spring tides. Again, from the best information we 

 can collect, the rise of surface from Westminster to Fulham is about 8 inches 

 per inile ; and as the effect of the alterations of London Bridge will be less 

 sensiljly felt here than nearer the bridge, we assume that tbe inclination, 

 after the alterations, will be 12 inches per mile, and the distance being nearly 

 6 miles, the water at Fulham will be lowered at low water 3 feet 9 inches less 

 2 feet, or 1 foot 9 inches, which will increase as we descend towards West- 

 minster Bridge, when (as before stated) the depression will be 3 feet 9 inches. 

 Again, as at Fulham. the surface will be lowered I foot 9 inches, this de- 

 pression will decrease upwards ; but as in any given length upwards, the 

 effect of the proposed alterations will also decrease, this depth (1 foot 9 inches) 

 will be felt a considerable way up the river ; for wc think it probable that the 

 efl'ect of the alterations may be sensible, in point of the navigation, for 6 

 miles above Fulham Bridge, or at Kew Bridge ; and that though it will really 

 extend higher, we apprehend that its effects will not be of any consequence 

 above th.at point. We believe there is no speculation in any of the above 

 numbers, excepting in the assumed increase of declination of surface ; for the 

 correctness of which we cannot vouch, but we have been guided by the con- 

 sideration that 4 feet 9 inches at low water, and about 9 inches at high water, 

 making together 5 feet 6 inches, will be added to the depth of water which 

 » ill pass through the bridge at every spring tide ; and by allowing an in- 

 crease of fall in proportion to the square of the increase of velocity or quan- 

 tity, and also by referring to the inclination in the upper part of the river, 

 say between Morllake and Teddington, as thown upon Mr. Whitwortli's sur- 

 vey, and making such allowance as from tbe difference of situation appeared 

 tons reasonable, we apprehend that we are not far from being correct, parti- 

 cularly between Fulham and London Bridge ; and it is hardly necessary, 

 after the above, to say that we agree in n|iinion w ith Mr. .Smeaton, that, by 

 this reduction of fall at the bridge, ' the navigation of that pjart of the river 

 will be materially affected.' It appears to us, from our own knowledge, and 

 from the statements that have been given to us, that although the increased 

 velocity of the river would have a tendency to restore the river to its ancient 

 depth, and in course of time would probably effect that object, yet that so 

 great a lowering at once would be productive of great temporary incon- 

 venience, unless artificial means were resorted to, to deepen the shoals, which, 

 even in the present state of the river, are attended with considerable hin- 

 drance to the navigation. Mr. Smeaton's opinion on this subject goes beyond 

 our ideas of time ; but, as great respect is due to his opinion, we extract it in 

 his own words: ' If this difference of bed,' that is, the difference above and 

 below bridge, ' is original, we must expect it to remain after the bridge is 

 taken away ; but if an effect, the cause being removed, the river would gra- 

 dually restore itself; but as this might probably take up 700 or 800 years 

 (the time it ha.s probaiJy been gathering), the work of restitution would go 

 on far too slowly to answer the demands of the present generation.' Our 

 opinion is. that the difference of level in the bottom of the river, above and 

 below bridge, is caused, in a great measure, by the pen of the bridge ; and 

 although we think that the work of restitution would be complete in less time 

 than stated by Mr. Smeaton, unless where the accumulation has got cemented 

 into a solid mass, which we have no doubt is in many places the case, yet, 

 both for the ptu-poses of present trade, and to prevent the shoals from beinjj 

 moved down tbe river by the current, and forming obstructions lower down 

 the river or below bridge, we think that ballasting to a great extent will be 

 expedient and requisite; as. in addition to the above reason, the stuff' that 

 is excavated from the upper part may be applied to raise ihe towing-paths 

 and banks, so as to meet the increased height of the high water, which will 

 occasionally be from 1 to 2 feet above the present level. One principal shoal 

 is close above London Bridge, on the Surrey side ; it extends almost half-way 

 across the river, and is even now occasionally above low water. This must 

 therefore be deepened to a considerable extent ; and to prevent the opening 

 of any of the proposed widened arches, which will he opposite to it, from 

 washing any part of it into the Fool, and settling upon the shoals below bridge, 

 it, as well as the other shoals, ought to be ballasted away before the proposed 

 arches are opened. In ref>:ard to Ihe navigation throvigh London Bridge, we 

 are of opinion that it will be very essentially improved by the proposed alter- 

 ations, and that the cause of the losses, accidents, and dangers to which the 

 ptissage is at present subject, from the great fall or shoot in the arches, will 

 be almost entirely removed. We have mentioned, that the velocity of the 

 current above bridge will be increased. Tbis will take place during both the 

 flood and ebb tide, but will be greatest in the latter ; and the increase of ve- 

 locity will, as before stated, be greatest Ijetween Westminster and L^cmdon 

 Bridges, in our calculation of the fall, we have supposed that the increase of 

 velocity will amount to one-half of the present velocity. This will, in many 

 ca.ses, be important, not only as regards the velocity itself, (as to which it 

 will sometimes be found of advantage to craft and sometimes probably other- 

 wise), but as the water will ebb sooner from all the wharfs, the time in each 

 tide during which the barges are afloat at the wharfs and when they can ffoat 

 to and from them, will be decreased. This will, so far, he a disadvantage 

 l3ut will occur only during the ebb of tide. It is evident, however, that it 

 will not be comiiensated by the increased velocity of the flood-tide bringing 

 tlie barges sooner to the wharf's above bridge, as the velocity of the flood will 

 not be so much increased as that of the ebb-tide, and although barges may 

 come up opposite to the wharfs sooner in the tide than they do at present, if 

 the channel is deep enough, they will not be able to get close to the wharfs 

 until about the same time of tide they do at present, unless a general artificial 

 deepening takes place opposite to each wharf. In some cases, however, barges 

 which may get opposite to the wharfs early in the tide, will be enabled by 

 having done so to draw in to the w harfs so soon as there is depth enough of 

 water to float them in, and, so far as this goes, the effect of this proposed 

 alteration « ill be useful. The great cause of shoals is the unequal velocity of 

 currents, and this inequality increases as the velocity mcieases; for there- 

 fore it is that floods, or great velocities, are always found to add to the shoals 

 of navigable rivers, aud lo deepen «hat was too deep before. The increased 

 current through the narrow' parts disturbs and carries down the materials of 

 the bottom through those narrow parts or deeps, and they are lodged upon 



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