1849."] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



223 



non-condensing engines quite untouched, and free for discussion at a future 

 period, 



June 26. — The paper read was " Observations on the Otstruct ions to Navi- 

 gation on Tidttl Rivers." By Mr. J. T. Habrisin, M. Inst. C E. 



The tirst part of the paper treated, in a general manner, of the circum- 

 stances affecting the deposition of materials and the action of water upon 

 them; and in the latter part an application of these circumstances was 

 made, in explanation of the formation of obstructions existing in the bed 

 and at the entrance of tidal rivers. 



Under the former head, the materials forming obstructions were first ex- 

 amined, the places whence they were derived, and the causes affecting their 

 initial removal ; cohesion, friction, the specific gravity and size of the mate- 

 rials, were shown to affect the question of their motion. The action of 

 water upon these materials formed the latter part of the subject. Under 

 tliis head, the character and effects of pure stream moiion and forced mo- 

 tion, in the form of a pure wave of translation, and of standing waves, were 

 severally considered. It was shown, that during pure stream motion the 

 water had the greatest velocity where the channel was deep ; that curves in 

 the channel gave rise to increased depth and velocity ; and an explanation 

 was given of the deposit of materials by the water after leaving a curved 

 channel ; that the effect of a pure wave of translation was, to scour the 

 shallows and deposit the material in the deeps ; and, as its momentum was 

 destroyed, to heap up a bank rising gradually. The effect of standing wave 

 motion of water was shown to be tlie formation of a succession of deeps 

 and shallows. 



Under the latter head, the first division treated of the action of river 

 water — first, in its own channel, when the subject of impediments, as piers 

 of bridges, weirs, &c., was examined ; 2nd, where it discharged into a large 

 basin devoid of tide, under which head the formation of deltas, &c., was 

 discussed; 3rd, when the basin into which it flowed was subjected to a rise 

 and fall of tide, but without perceptil)le current. 



The second division treated of the action of the sea without the entrance 

 of the river. Attention was drawn to the effect of the situation of the en- 

 trance, with respect to the direction of the tidal wave. It was shown, that 

 in some cases, part of this wave set directly up the river, as in the case of 

 the Severn, &c. As a branch of this subject, the peculiarities of the tidal 

 action, described in a communication to the Royal Society by Capt. Beechy, 

 as existing in the Irish Sea, were commented upon, and an explanation 

 offered of some of them. In other cases, the tiilal wave setting at right 

 angles to the direction of the river, when the wave which passetl up it was 

 generated at the entrance. The deposition of materials near the mouth of 

 rivers by along-shore currents, and by the wind waves, was then briefly 

 touched upon. 



The third division treated of the action of the water in entering rivers so 

 placed, that the wave was generated at the entrance. The circumstances 

 which affected the quantity of water entering were considered ; it was shown 

 to be limited by the width and depth of the entrance, and the rise of the 

 tide ; and again, by the degree of freedom with which the momentum gene- 

 rated is transmitted. It was also shown that this freedom of transmission 

 depended chiefly on the depth of the water ; and other circumstunces affect- 

 ing it weie explained. 



Under the fourth division, the removal of bars by the ebb tide was dis 

 cussed ; and the propriety of the water having a free motion, and not being 

 forced over the bar, was shown. It was argued, that bars are frequently in- 

 creased by a narrow or shallow channel at the entrance causing a head of 

 water, and the consequent formation of a standing wave between it and the 

 bar. The deeper the channel could be maintained, and the further the water 

 could be made to flow up it, the better would be the eft'ect of the ebbing 

 waters upon the bar. It was shown that the deep water found within the 

 entrance of many rivers is caused by the flood tide, and that an improve- 

 ment in the bar would probably have the effect of lessening this depth, 

 which, in many cases, would be considered a disadvantage. 



The filth division treated of the effect produced on the bed of the river's 

 channel. The difference in the motion of the water on the flood and ebb 

 was shown. When the tidal wave was oscillatory at the entrance, the ten- 

 dency of the tidal action was to draw out to sea the material lying in the 

 bed of the channel at the entrance, and to heap up sand-banks in the upper 

 part of the estuary. When the tidal wave was generated at the entrance of 

 a bottle-necked estuary, the formation of sand-banks within the entrance, 

 with tlie false channels which accompany them, was explained, as being the 

 result of the flood tidal action. The effects produced by the ebb tide were 

 shown to be generally similar to those described as produced in rivers proper. 



The sixth division drew attention to the remedies necessary for prevent- 

 ing obstructions ; and to that end it was urged that the sources whence the 

 materials are derived should be first attacked ; the possildlity of checking 

 the progress of shingle along the coast towards the mouth of rivers, and its 

 entrance when there, as well as the washing down of the detritus from 

 the upper part of rivers, was discussed; and it was agreed that much might 

 be done by groyning the coast, carrying out piers at the entrances and in the 

 upper part of the river, by groyning the banks in some places, and allowing 

 a free scope for the deposit of the material which is being washed down in 

 others. The suliject of piers at the entrance of rivers was then more freely 

 entered into, and the effects produced by their being built too close together 

 and curved were discussed. Some points which it seemed desirable to :ittpnd 

 to in fixing the lines for confining rivers, were generally considered ; aail the 



paper ended with the expression of a hope tliat it might lead to discussion, 

 and a further collection of facts, upon which alone any sound theory can be 

 founded. 



After the meeting, Mr. F. A. Carrington exhibited in the Library a beauti- 

 ful model, in relief, of portions of the counties of Lancaster, Yorkshire, 

 Cheshire, Notts, and Derbyshire, extending from Manchestei to Lincoln ; 

 and the Humher, east and west ; and from Leeds and Bradford to Chats- 

 worth Park, noith and south. These models show at a view the whole phy- 

 sical geography of a district, and are admirably calculated for projecting 

 works of both civil and military engineering ; and if they were a step in the 

 sanitary improvements of towns, the progress would be more certain, and 

 less costly. 



The meeting was adjourned until the commencement of the next session, 

 which it was proposed should be at an earlier period than heretofore. 



ROYAL INSTITUTE OF BRITISH ARCHITECTS. 



June 4. — T. Bellamy, Esq., V.P., in the Chair. 



A paper was read, '"Ort the Building Materials employed at Paris, and in 

 the Valley of the Lower Seine." By G. Burnell, Esq., Jun. 



The author give a detailed account of the qualities of the piincipal build- 

 ing materials used by the architects and engineers of Paris and the valley of 

 the Lower Seine, accompanied by some statistical statements of the quanti- 

 ties used in those localities. In comparing these with the quantities em- 

 ployed in England, the most remaikable difference appeared to exist in the 

 greater use in this country of iron, especially cast iron, which may be ac- 

 counted for by that material being mucii dearer in France. The use of gyp- 

 sum in France, which we call Plaster of Paris, instead of morlar made en- 

 tirely from lime, for filling in the internal partitions and for forming the 

 floors and ceilings of the rooms, was alluded to as rendering the buildings 

 less combustible than in England. Mr. Burnell commented on the bad sys- 

 tem adopted in building some of the modern houses in Paris, where, by using 

 squared stones for the fronts next the streets, rubble stone for the party- 

 walls, and lindier Iraniirig filled in with plaster for the back walls, — fissures 

 and cracks are produced in consequence of the unequal combination and the 

 dififerent expansive jrower of the nraterials thus applied. For the covering of 

 the roofs, slatci and tiles are used in France, but zinc is more generally ap- 

 plied in that country than in England,- — the dryness of the climate rendering 

 it less liable to corrode than with us; being much cheaper than either copper 

 or lead, it is frequently employed where those metals would he applied in 

 England. Mr. liurnell urged the necessity of more accurate and detailed 

 investigations of the chemical properties of building materials than have, 

 hitherto been considered necessary, — be observed that "little is here known, 

 comparatively speaking, of the chemistry of the art of building, that little 

 having principally been gleaned from the scientific researches of the French 

 authors." 



A discussion ensued on the subject of the greater amount of resistance 

 ofi'ered by stones when used in the direction of their natural bed. 



The Report of tlie Council to the Annual General Meeting, May "111, 181'.', 

 has just been issued, from which we collect the following extracts; — 



The agitated state of Europe during the past year, following immediately 

 upon the vast financial embarrassments of the year 18t7, has not failed to 

 irroduce a serious eflfect on the arts, to which a state of peace is ever favourable. 

 The council feel that to these circumstances may be attributed the absence 

 from this report of one feature always hitherto satisfactory, — the notice of new 

 works of magnitude and interest, in which art and science might have acquired 

 further development. Symptoms of returning national prosperity are how- 

 ever to be observed, and as these, if realised, cannot fail to operate bene- 

 ficially on all the arts of design, it may reasonably be expected that a future 

 council will be enabled to make a more favouralile record than can be done 

 on the present occasion. But notwithstanding this barrenness of matter as 

 respects art, the fiflds of science have nut been unproductive. 



The various accidents which have occurred during the last few years in 

 some extensive buildings in the manufacturing districts, and likewise in works 

 connected with railways, from failures of cast-iron, have given rise to the 

 question as to the dependence to be placed on that material ; this has 

 attracted the attention of the government and of several scientific men. A 

 series of elaborate and accurate experiments, on a large scale, have been 

 gone through by our honorary member. Professor Ilodgkinsou, and various 

 expedients have been suggested by practical men; amongst others Mr. 

 Merries Sterling's patent method of increasing the tenacity of cast-iron by 

 the admixture of wrought scraps, promises important results. As iron has 

 been largely introduced of late, and is likely to be still more extensively 

 employed in the construction of buildings, the problems to be solved demand 

 tlnit the most serious attention should be bestowed upon the system of 

 wrought-iron framings, frequently adopter! by French architects and 

 engineers, and perhaps instructive principles might be derived from a com- 

 parison of the relative values of the systems in operation in France and in 

 England. 



Fire-proof construction is becoming of more general adoption, and 

 various schemes have been brought under the attention of the Institute at the 

 ordinary meetings. The revival of the ancient mode of constructing vaults 

 and arches, by means of hollow bricks, as employed in a somewhat different 

 form in the vaulted ceiling of St. George's Hall at Liverpool, recently' cuo- 



