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pavement. It would be hardly possible riage ways, there could be no doubt that to overrate the importance of having compressed asphalt was the best for that streets permanently open for traffic. purpose. He had paved about 25,000 Again the rapidity with which it was yards of footway in the parish of Claporiginally laid, compared favorably with ham, since 1872. Various small speciother materials. In Paris, he believed, mens were first laid. Then about 1,000 a given area of each road had to be yards of Barnett's asphalt, 1 inch in opened in eight days; in London, four- thickness, was tried; the cost was 48.6d. teen days had been found ample time to per square yard, and it was still in extake up the old stones and lay asphalt istence, and might be considered a fair and concrete, and permit traffic. The path. It was afterwards thought desirauthor had suggested the use of asphalt able to make the best footpath that concrete costing 80s. per cubic yard; could be obtained in asphalt, and, after this was too high a price, because a bitu- considerable investigation, the Val de minous concrete composed of ballast, Travers compressed asphalt was selected, coal tar, and creosote oil, could be laid and more than 20,000 superficial yards for 21s. per cubic yard, 6 inches in thick of that material had been Jaid. A great ness. It had been tried in Liverpool object was to secure uniformity of pavunder sets with manifest success. By ing throughout the district, also facility using a concrete of this kind the work in executing repairs. It was somewhat of laying a road could be shortened by unfortunate that transverse cracks had the difference in time required for Port- appeared about every 6 or 8 yards. land cement concrete to set and that re- They made their appearance from about quired for bituminous concrete, which three weeks to twelve months after the was a few hours only; so that a road fit path was laid. Some of the cracks were for traffic might be laid in London in cut out, when it was found that correeight days. There was no reason why sponding cracks existed in the concrete this kind of foundation should not be below. The whole piece was cut out, and equal to Portland cement concrete; and new concrete put down, which was kept it was well worth the attention of muni- exposed for six or eight days to harden. cipal engineers and asphalt companies. Then a thin coating of mastic asphalt With regard to foothold for horses, or was laid over it, previous to the powder rather the absence of it, the city engi- being restored. Similar cracks, howneer had demonstrated, by a series of oh- ever, appeared again in the same line, servations of an exhaustive nature, that and it was difficult to account for them. saphalt occupied a position between He thought to some extent they dependwood and granite, in the order named: ed upon the concrete. Great pains were and the popular outcry against the slip- now taken with it, and 6 parts of ballast periness of asphalt arose from the greater to one part of cement had been substinumber of horses falling at one time. tuted for s parts of the former to 1 part He was strongly of opinion that the au- of the latter, clean Thames ballast thor was correct when he stated that being used; it was mixed with very this absence of foothold was due to little water, and was well beaten with want of cleanliness. The city corpora- shovels. The cement had been tested, tion had recently put down a number of and had broken at a pressure of 450 hydrants all over the city area. If these lbs. to the square inch after seven were utilized in cleansing asphalt, the falls days, during six of which it was laid in of horses would be reduced considerably water. The concrete for the last piece The author had made no allusion to the of paving was kept open for fourteen fact that during the past few years the days, so that it was dry before the pownew pavements of Paris in asphalt der was laid upon it; the footpath was were much inferior to those formerly previously rolled and consolidated; and laid. It had been asserted that this was this path had shown very few cracks. owing to the use of the Lobsann asphalt, He was inclined to think that compressed which did not contain sufficient calcare- asphalt was scarcely so durable as had ous matter in the natural rock.
been generally supposed. The mastic Mr. A. SOUTHAM remarked that where asphalt he believed was somewhat hardit was desirable to lay asphalt on car-ler, though it was objectionable from
the uncertainty of its mixture, from the covered that the pavement was affected difficulty of making the repairs to match by the humidity of the atmosphere or the rest of the paving, and from the fur- by rainy weather. They sometimes naces for melting it having to be in the found, when the drying process had set street. He had not yet decided whether in, that there was a little streak through it was advisable to continue the use of the foot way, but in a day or two it compressed asphalt, or to resort to the entirely disappeared. On the grounds mastic. He was surprised at the im- of economy, noislessness, and cleanlimense area of footway paving laid in ness, after the many pamphlets that had Paris, but the author had not stated of been written and the many reports prewhat it was composed. Mr. Southam sented, there could be no doubt as to the presumed that was chiefly mastic. The superiority of asphalt; and he believed Val de Travers Company had assisted that compressed asphalt for roadways him greatly by their willingness to lay possessed greater advantages than any the concrete in any way that might be other material. The roadway in Cheapdesired, and to keep it exposed for any side had been laid ten years, and it was length of time. Their manager had still in existence. The heaviest traffic in suggested that lime concrete would pre- the world passed over it, but it had vent the cracking, and accordingly one never been interrupted for an hour. The line of path had been laid with it. It repairs were done early in the morning, was not a success; there were no trans- and the result was that Cheapside posverse cracks, but it had failed from the sessed a clean, noiseless, and cheap roadsettlement of the concrete, which was way, which, as he knew from the shopnot yet hard, and had cracked longitudi- keepers, was regarded as an enormous nally from the frost. The concrete in boon. As to the objection on the grounds this instance was laid from fourteen to of slipperiness, that, as the author had eighteen days before being covered with explained, was a question of cleansing, asphalt. Very few cracks had appeared and not a question of asphalt. If engiin the city paths. The foundations were, neers and district surveyors would imperhaps, more solid, and owing to the press upon the Vestries of London the greater traffic brought to bear upon them, importance of spending more money in the asphalt was more compressed and cleansing the roadways, they would conkept in its place. The asphalt in Clap- fer an immense benefit upon the comham had suffered from cracks during the munity. The condition of the lanes, late severe winter, but they had all been slums, and alleys of London was deplorlongitudinal instead of transverse, and able. The rejected granite sets and after the frost they had closed and did York flagging from the richer districts not look so bad. In this district the use were transported to those localities, of asphalt would probably be largely ex. where the children of the poor were tended if a perfect paving could be laid. congregated, and where they played He would be glad to know which was about all day in puddles. If the authorthe best description of asphalt to use for ities would only give them asphalt, they footway paving.
would be doing something towards mak. Mr. II. C. Scott observed that, as a di- ing life tolerable to many who now rerector of the Val de Travers Asphalt garded it as little better than a burden. Company, he might be permitted to re Mr. W. B. Lewis asked if any one acfer to their experience of London road customed to lay asphalt upon concrete ways. The question of cracks upon com- had ever tried the plan of laying the pressed asphalt footways was one that he concrete in slabs, with joints, in order to frankly confessed had once given them prevent cracks. Engineers who had some concern; but they were of opinion used concrete in large masses were aware that the fault would only last a short that the difficulty of cracks frequently time. In going along the Cheapside occurred. At the Victoria docks, in one pathway, which had been laid between wall 14 mile long, and 33 feet or 34 feet three and four years, he had not observed high, of solid concrete, there was a hair any cracks; and in Moorgate Street, crack through it at about every 14 feet. where it had been laid four or five years, He presumed that this arose from the there were very few. He had not dis- material being homogeneous, and that
there must be expansion and contraction crete, and there was only one way to get somewhere. Possibly the cracks in the rid of them-a plan that he adopted ten asphalt pavement arose from the concrete years ago-never to lay more than nine being laid in one continuous mass. feet length of concrete at once, bringing
It must have yielded somewhere to at- straight joints across the footpaths by mospheric influences, and consequently inserting boards, withdrawing them cracked. If it were laid in slabs, with when the concrete was soft, and leaving joints ever so small at intervals, possibly the fissures open for a considerable that would get rid of cracks in the as- period. The great trouble in getting phalt.
concrete laid was, to induce the workMr. John KNIGHT said that Portland men not to use too much water. It cement concrete expanded and contracted could not be laid too dry, especially according to the weather, while asphalt, where it had to be covered with Portif laid in a mastic state, neither ex- land cement or asphalt. A long discuspanded nor contracted, whether tinch sion had recently taken place at the or 1 inch in thickness. It appeared that Royal Institute of British Architects the asphalt in Brighton had not cracked on Portland cement and concrete, and it because it was in an elastic state, while seemed to be the general opinion that that laid in Hove in a compressed state one of the chief troubles connected with had cracked. The reason for the crack- concrete was the over use of water by ing was that it was not of sufficient workmen. If it was laid almost dry, thickness-only i inch; and the same and thoroughly rammed and jointed at reason applied to other cases that had intervals, the joints being left open until been mentioned. No cracks had ap- the water had evaporated, it might be peared in Cheapside or in Moorgate covered with asphalt without any fear of Street, because the asphalt had been laid cracks, provided there was a solid subof sufficient thickness—1 inch. Com- stratum.
But where it was laid upon pressed asphalt should not be laid less clay difficulties would invariably arise, ihan that thickness, otherwise it would unless there was interposed between the crack in every direction. The first as- concrete and the clay a considerable phalt of the Val de Travers Company amount of hard, pounded, dry filling for that he had noticed was in a mastic state. drainage purposes. The most difficult It did not last very long; it was not pavements were those laid upon a clay suitable as a mastic asphalt, but as com- substratum, and he knew of no mode of pressed asphalt it was very good. When curing the difficulty except by getting a surveyor saw a piece of York stone, out a considerable depth of clay, and he could express an opinion as to whether replacing it by dry material. For coverit was good or bad; but he could pass ing roofs, arches, and the like, he preno such opinion with regard to asphalt
, ferred the mastic to the compressed aswhether in a mastic state or compressed. phalt. For level roadways and footThe goodness of the material was only paths there could be nothing better than to be ascertained by its durability. The the compressed asphalt for pavements, best piece of asphalt in the city was laid on the ground of cleanliness, but the in a mastic state in King William Street, danger of horses slipping in greasy weaeight or nine years ago, and it still ex- ther was a serious one. He had often isted as when first laid, with the excep- passed through Cheapside in muggy tion of a few repairs for gas and water weather and seen several horses down at purposes.
one time. Whether that could be obMr. J. FOGERTY observed that he had viated the did not know. The question had some years' experience, both as an had not been fully dealt with in the paper, architect and as an engineer, in laying and he hoped the author would allude tó pavements and in the use of asphalt and it in his reply. The only remedy that Portland Cement for the covering of could he suggested was a thorough cleansroofs and other structures. He did not ing, which, so far as Cheapside and believe that a layer of inch of asphalt similar streets were concerned, could of any kind was sufficient, especially in only be done during the hours of traffic footways. The chief cause of cracks by means of numerous hydrants, and the was, he thought, to be found in the con- ! constant use of hose-pipes with large
side apertures, such as those used in go through to the surface of the asphalt. Paris, to carry off thc washings into He did not agree with those who had drains or reservoirs. Allusion had been said that the concrete should not be laid made to the operations of gas and water in long lengths. He thought the more companies which destroyed the roads men that were employed, the more quickly and pavements in cities. Some twenty the concrete could be laid, and the longer years ago, the parish of Marylebone the lengths the better. The work was offered a prize for the best section of then all of a piece, and was in the best subway, and it was won by a young condition to receive the asphalt. student in the engineering class of Uni Mr. E. J. HARRISON had under his versity College - Mr. Davis. Since that control, on behalf of the Val de Travers time very few subways had been con- Company, the majority of the asphalt structed in London, and even in those, roadways in the City of London. The gas and water companies were very un- history of the compressed roadways in willing to place their pipes. The only London was soon told. The first laid objection he had heard was that the es was that in Threadneedle Street in 1869. cape gas in such enclosed places It consisted of a layer of two inches of would be dangerous. On that point he Val de Travers compressed asphalt on a should be glad to hear the experience of concrete foundation. He had no doubt the city surveyors who had charge of that many members had noticed it when streets and subways in which gas pipes it was being laid, as it created a great were laid.
sensation at the time. He remembered Mr. HENRY GLENN attributed the looking at it and wondering how many cracks that had occurred in the Val de weeks it would last. It was now within Travers asphalt to the want of a suffi- two months of being eleven years old, cient quantity of bitumen. Heating the and was still, as it always had been, in powder drove off the bitumen to a large good condition. Some new Aberdeen extent, and if the quantity was reduced, granite had been laid beside it for a as stated in the paper, to 94 or 10 per trial of endurance, and seven years aftercent., cracks would be sure to occur in wards it had got into such a state as to severe weather. In the case of mastic require re-dressing and re-setting ; asphalt, the difficulty could be obviated, but that was not done, because, when because the cauldron was in the street; and the inhabitants of the street learned if the asphalt did not contain a sufficient that the street was going to be quantity of bitumen, an addition could closed for repaving, they expressed be easily made to it, and an experienced a preference for an asphalt roadway, foreman would know what quantity to which the city authorities gave them. add. Some reference had been made to Since 1869 the progress of asphalt roadmastic asphalt not wearing so well as ways throughout London, though rather other kinds of asphalt. A good deal slow, had been steady. There were now depended upon the size and quantity of in the city of London alone 12,000
There ought not to or 14,000 thousand lineal yards of be too much, and the size should not be paving, covering a superficial area of too large. If it was too large, it would 150,000 yards. The Val de Travers work out, which a small piece of grit Company had upwards of one hundred would not do. When the Barnett Ag- roads under their charge, many of them phalt Company was in existence, it was being the main thoroughfares of the the practice to use the large grit, and city, having a concentrated and heavy the consequence was that nearly all their traffic; and the area would be considerwork failed. He had seen concrete laid ably increased during the present year. down in 6 or 7-feet lengths, and allowed One noticeable feature with regard to to get thoroughly dry at the end; and the use of asphalt was the great number when the next layer of concrete was put of preparations that had been tried. on, it had not been sufficiently wetted Between 1870 and 1880 more than fifand properly jointed. In such a case teen had been employed in London, most cracks would arise through the concrete; of which had proved failures. His Comand if the asphalt did not contain a pany had already replaced eight or ten sufficient quantity of bitumen, it would l of them, not always under favorable cir
cumstances for the company. In order and one was from the Poultry, a re-lay to shorten as much as possible the time which was only three years old. The during which the streets were closed for roadway of the Poultry was only three re-paving, the company had generally years old, because the houses on the agreed to lay its asphalt upon the old north side were set back several feet concrete foundations, some of which had three years ago, necessitating an alterabeen almost as bad as the asphalt that tion in the footway and roadway. The had been placed upon them, while company laid down new concrete where others had been damaged by the traffic necessary, and faced up the old, and passing over them after the asphalt had then spread asphalt on the top of it. worn out. In main thoroughfares likeThey had good weather, and with the those of London, where every hour's assistance of the authorities, and the stoppage of the traffic affected not only good will of all the inhabitants, they the occupiers of the particular street, managed to carry out the work in sevenbut more or less remotely the traffic of teen days. It had proved very satisfacthe whole of London, the use of a pav. tory, and they had never had occasion ing material which required constant re- since to spend a penny upon it. When newals or freqnent repairs was a serious Mr. Deacon's Paper on “Street Carriagematter. He certainly could claim on way Pavements” was read and discussed, * behalf of the Val de Travers Company, very little was said about asphalt roadthat it had never closed a city street for ways, Mr. Deacon stating that he had repairs, and such repairs as it had done had no experience of them; the gradients had never affected the traffic in any ap- in Liverpool not allowing the use of aspreciable degree. A very little hole, if phalt. He had been struck with the neglected, speedily became a big hole, unanimity with which every speaker and for their own interest, if for no other on that occasion urged the necessity of a reason, they had always taken care of solid foundation for a good road. Asthe little holes; the repairs, therefore, phalters were especially of that opinion. had been generally done on a small area, An asphalt road was in reality a rarely exceeding 2 or 3 square yards, and crete road with a surface of asphalt put early in the morning before the traffic upon it to carry out certain ends. If commenced. The openings for gas and the concrete foundation were taken away, cuttings for water pipes, which were or tampered with, or negligently laid, generally a source of great obstruction, asphalt itself would form a very sorry were less serious with an asphalt road paving. In dealing with that question, than with any other paving material. one important point to be considered was A hole could be cut exactly the size re- the obligation under which the engineer quired, and when the work was done it or surveyor was placed to have the road might be made good immediately. More closed for paving for the shortest posover, leakages in mains under an asphalt sible time. For that reason his company road were less frequent than under any had always urged the desirability of layother material, on account of the absence ing a concrete composed of a quick-setof vibration. Still those cuttings had to ting Portland cement with the best obbe made, and frequently there was a trifl. tainable ballast. As far as his experiing settlement of the new work, pro-'ence went, if a lime concrete was sealed ducing hollows and forming puddles, up hermetically by asphalt on the top, which were more conspicuous on an as- there was no knowing what might happhalt surface than on any other; so that 'pen underneath; whereas, if Portland he should be glad to see the introduction cement concrete were left open for a few of subways under the London streets. days and then covered with asphalt, At the request of the author, he had had engineers could form a pretty good idea small samples of the roadways cut out of what would happen. In London they from some of the oldest roadways hav- were indebted to the French asphalters. ing the heaviest traffic, and they were on for all that they had first learned as to the table for inspection. Two of them the nature and treatment of asphalt; but were from Cheapside, ten years old; one he thought that they had now beaten was from old Broad Street, and another their instructors, putting down better from Gracechurch Street, nine years old; . Vide Minutes of Proceedings Inst. C. E., vol. Iviii., p.1.