Author: Knapen, A
First published: N/A
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MR. W. J. H. LEVERTON proposed a vote of thanks to the author of the paper, to M. Bertrand, to Count Lewenhaupt for having described the lantern slides which illustrated the paper, and to the Chairman for having interpreted Count Lewenhaupt's remarks. Referring to the squeezing out of the mortar used in the walls of the Palace of Versailles, he said that, at the time the Palace was built, it was common in England to use chalk lime mortar, which, of course, was very poor stuff. He asked if that kind of mortar were then used in France also, because, if so, he was not surprised that it had squeezed out. With regard to damp courses, the author's experience seemed to be entirely against English practice. Everyone in England was horrified if a damp course were omitted; its omission was considered to represent the very acme of jerry building, and yet according to the author, it was of no use. The author had stated that, even if the horizontal damp course were an efficient obstacle to the penetration of moisture, its lower specific heat would cause condensation on its upper surface, the moisture resulting from which would be taken up again by capillarity and would rise in the wall. Mr. Leverton sald he took it that the moisture resulting from condensation would not be so great as the moisture which might arise from damp soil, so that, where there were two evils, it was better to choose the Lesser and to put in a damp course. With regard to the tubes inserted in the walls for the extraction of damp, he said they all seemed to be at a height of about 1 ft. from the ground, and something like 18 in. apart, so that they were inserted at that part of the wall which contained the most damp. He asked whether the buildings really did have damp courses when the tubes were put in, or whether the tubes were put in as a substitute, and whether tubes had ever been put in at a higher level. He was glad to hear the Chairman's remarks with regard to iron ties in hollow walls, because he had always thought that in about twenty years they must disappear, through rust. Some people contended that if they were dipped carefully in red hot tar they would last, that there was no visible evidence of that, as the walls containing them were sealed up. A friend of his, who was carrying out some alterations to a house with hollow walls, had had to take out a piece of wall about a yard square. He had put his walking stick inside the wall, and had been able to swing it round, so that there were no ties there. There was no evidence that they had been left out by the builder. In his view, bonded bricks, which had been used instead of iron ties, were far more effective, although more expense; if good bonding bricks were put in, they would last as long as the walls would last. Generally, with bonded bricks, the outer part was one course lower than the inner, so that any moisture which resulted from condensation on the brick had to go up-hill in order to get to the inner line of the concre
Sir,-I beg to enclose cheque. . . . I feel sure yod should meet with a very ready response from ever member. The scheme is a highly excellent one. Might I also say in passing how greatly the work of the Institution is appreciated through the length and
breadth of the land. Coming in touch, as I do, with some of the largest engineering works in various parts of Great Britain frequently each year, meeting in the course of my daily labours most of the Municipal engineers and public works Contractors in this country, I have an exceptional opportunity of learning the general opinions of the Building and Civil Engineering World; and wherever I go at every point of the compass, the recent growth and active policy of the Institution is commented upon with both surprise and pleasure. More especially is this so with the rising generation of those engaged in structural work -the young are always for progress. The activities of our Council and Committees with regard to Registration and admission by examination seem to have created widespread interest and gratification in particular, and if only I could voice the various expressions which have been made to me not only by members, but by the general public, I feel sure those gentlemen who have given their services so generously in the different offices, and the hard-working official staff, would feel
in some small measure repaid for their labours. If you deem fit, you are at liberty to publish this letter.-Yours, &C., R. D’ARCY SWAINSON
The subject of the transverse bracing of bridges appears to have received comparatlvely
little notice at the hands of English writers. The relatively few works published in this country dealing with matter relating to bridge design either ignore the subject almost entirely or dismiss it with only a cursory notice. On the other hand Continental and American writers have for many years past given to this subject that prominence which it both needs and merits. The theory of the design of transverse bracing has been placed by foreign authors on a fairly rational basis in so far as such design is susceptible of close theoretical treatment. Possibly the prevalence of the greater number of large span bridges abroad has been responsible for focussing attention on this branch of the subject since in larger spans the transverse bracing is more susceptible to proportionate design and is more urgently necessary than in smaller spans.
Professor J. Husband