Issue 10

Sir,-Mr. Arthur E. Pierce objects to the word " discarded " as used in my article, but his objection is not relevant.

The accompanying diagram provides an easy and rapid method for ascertaining the approximate number of concrete blocks or bricks contained in any shaped stack. It is assumed that the blocks or bricks are of a uniform standard size, so that the number per cubic foot can be accurately computed. All that is then necessary to do is to measure the stack so as to ascertain its cubic contents in feet. This done, a straight edge is placed across the three columns in the diagram, regulated so that the right hand side touches the number indicating the cubic content of the stack and the left hand side touches the outer colulm at the point indicating the number of blocks or bricks in a cubic foot; the straight edge will at once show on the intermediate column the number of the articles in the stack.

BEFORE Sir John Wolfe Barry was called into consultation, the main outlines of the Tower Bridge had already been decided upon. Sir Horace Jones, the City Architect, had submitted several designs to the Bridge House Committee, which, evolving through several stages, finally assumed a form not unlike the actual building. It may be of interest to study some of Mr. Horace Jones’s preliminary sketches, because these throw light upon the aesthetic problem which required to be solved. Figure 3 shows his first design for a bascule bridge, while Figure 4 was the one which held the field when Sir John Wolfe Barry was appointed engineer to the scheme. It was considered that any arched form of construction (such as Figure 3)across a span to be used by masted ships was inadmissible, and that whatever headway was given should be absolutely free of obstruction throughout the whole of the span. Sir Horace Jones, unfortunately, died in 1887, when the foundations had not made much progress, and up to that time none of the architectural designs had proceeded further than such sketches and studies as were barely sufficient to enable an approximate estimate to be made of the cost. After the death of Sir Horace Jones, the general architectural features of the Parliamentary sketch designs were preserved, but it will be seen that the structure as erected differs largely therefrom both in treatment and material. The width and, consequently, the weight of the bridge was increased by the requirements of Parliament, and the span of the central opening was enlarged from 160 feet, as originally intended, to 200 feet. At the same time the provision of lifts and stairs to accommodate foot passengers when the bridge was open was felt to be a necessity. It thus became apparent that it would not be possible to support the weight of the bridge on towers wholly of masonry, as in the first design, unless they were made of great size and unnecessary weight. It was therefore necessary that the main support should be of iron or steel, which could, however, be surrounded by masonry, so as to retain the architectural character of the whole structure. It was clear that in any event a large part of the steelwork of the towers must be enclosed in some material, for the moving quadrants project upwards some forty feet from the level of the roadway, while the stairs and lifts also required protection from the weather. It thus became a question of surrounding the towers either with cast-iron panelling or with stone, and eventually a granite facing with Portland stone dressings was adopted. A. Tryston Edwards

In this article the writer is dealing. with some additions to his previous, paper published in the April, 1925, issue of the "Structural Engineer." (Vol. III., Number 4). The underlying theory is given in that issue and is not repeated here. Harry Zimmerman

Among other work with Armstrong’s firm was the connection of the hydraulic pressure mains between the East India Docks and the West India Docks. The connection was to be made along the Blackwall Railway, but a difficulty occurred in passing Poplar Station which threatened to stop the work altogether, and it was not until a happy thought occurred to me that we got permission. I suggested that we should carry the pipes along the back of the platform and cover them with a continuous seat for the passengers, which was done. The firm erected a small hand-power swing bridge over the canal in Woolwich Arsenal, on cast-iron screw pile cylinders sunk in the bed. After it was completed it was desired to put in diagonal braces between the piles, but this could only be done when the water was drawn down in the canal to its lowest level. This was arranged for one Sunday, and I undertook to see it carried out. It was in the depth of winter, the canal was covered with ice and there was a strong north wind blowing right up the canal. On my arrival the men had got a raft upon which to work to remove a flange bolt from each pile, but the joint was some six inches below the water level and the bolt had to be driven upwards. They tried it for some time, but the bolt held firm, and they struck work, saying it was too cold. It wasas determined it should be done if possible, so I took off my coat and laid down on the raft with the water spurting up between the joints and freezing on the top. I got the bolt started, and the men thus encouraged completed the removal. We then found the tie-rods as sent from Newcastle were too long, so that the next step was to send out into the town and find a smith to come in, cut and re-weld them. This was done for a reasonable payment and the work was completed the same afternoon. It was a chilly experience, but I had another sort some years later on, to counterbalance it. This was the examination of the reinforced concrete foundations under some electric furnaces in Scotland, also in the depth of winter. The outside temperature was 26 deg. Fahr., but in the vaults under the furnaces where I stayed for twenty minutes taking measurements and making sketches, the temperature was 176 deg. Fahr., only a rise of 150 degrees! Professor Henry Adams When hydraulic wagon lifts were first used to pass

BEET sugar manufacture, the younger competitor of the cane sugar industry, had its birth in 1747, when a German chemist drew attention to the sugar content of the beetroot, but it was not until 1799 that a method of extracting sugar from the beet was invented. Shortly afterwards, a factory was erected in Silicia under the patronage of the King of Prussia, who partly financed the undertaking as an encouragement to German agriculture. Numbers of other factories rapidly sprang up in Prussia and Bohemia, and in 1811 the industry was introduced to France by the Emperor Napoleon, who desired to make France independent of outside sugar supplies. Although the industry was at first a purely military measure, and therefore declined when peace once more settled over Europe, it had as rapid revival about 1830, when European farmers realised the advantages of beetroot cultivation, and offered the sugar factories supplies of roots at low prices, and the growing of beetroots and the manufacture of beet sugar spread rapidly throughout Europe.

ALTHOUGH the subject of The Education has been discussed for many years at such length that some people are tired of it, we must go on with it because it is vitally important, and because there are still differences of opinion that must be realised before we can hope adequately to deal with the problem. Ewart S. Andrews