Issue 12

Mr. F. Lindstead, replying to the discussion on his paper, said, “I am aware that this is not the time nor place to reply to the criticism of Mr. Deane, but since the opportunity presents itself I beg to reply that when I mentioned in this paper that the ordinary U tube manometer was not suitable for measuring the small differences in the height of head of water due to smail pressure, I assumed that the engineer interested in this class of work would be familiar with the tilting manometer used by the author, and which has now been in use and on the market for some years, and is more accurate and sensitive than the one described and used by Mr. Deane; it is also portable and compact which is a great advantage when used on a works, and it also would not be practical to use methylated spirits as used by Mr. Deane, in the place of water in the manometer in the neighbourhood of a rotary kiln owing to evaporation caused by the heat from the kiln. A description of the tilting manometer will possibly be of use here. As will be seen from the sketch the manometer consists of a U tube 1, 2, 3, provided with stop cock 4, and microscope D mounted on a frame A, which is supported on three steel points 5, one of these points being the centre of the micrometer wheel C. The frame A is supported on the steel points 5 on the frame B. The microscope D is supplied with a horizontal hair line which is sighted on the water level or meniscus in the limb 2. The pressure is applied to the ends of the limbs 1 and 2, and the micrometer wheel C is rotated until the hair line in the microscope D again corresponds to the water level in the limb 2. The head is read off on the micromefer wheel C and scale E; this reading requires multiplying by a constant depending on the dimensions of the instrument which gives the actual head of water. For a constant pressure this instrument can be read to 0.001 inch head of water. The author has used this instrument together with others of similar type with entire satisfaction.

LEGISLATION in regard to housing in the Netherlands, may be said to date from 1901. In that year the Dutch Housing Act was passed. Before 1901, however, many local authorities in Holland had dealt, to an extent, with the problem of housing in their respective areas, and there had been much criticism of the housing conditions generally, particularly in the great centres of population. The general standard of housing accommodation in the Netherlands, it will be generally admitted, is much inferior to that in England, in every particular, and the demands of the people, it would appear, are more easily satisfied, not only in regard to the superficial area of the dwellings, but also in regard to the planning and to the provision of the many conveniences regarded as essential in English homes. Sir Charles T. Ruthen

THE problem of producing perfectly moulded ornamenture, corners, window and door trim, in the surfaces of concrete buildings is at least partly solved by the practice of a Canadian concern. The method used is to pre-cast, or manufacture in advance, in a factory, all of the decorative features of the surfaces, which are inserted and supported in the forms until the structural concrete, forming the body of the wall, is deposited around them.

The following simple problem in Graphic Statics is supplied bg The Bennett College, Sheffield, the Governor of which will give a prize of 10s. for the best solution. In allotting points, neatness will receive the same consideration as accuracy.

The Board of the Swedish Concrete Association has commissioned the author to work out a method of testing plain cement on the building site without adding of aggregates, as sand or gravel, and to conduct research work into thc possibilities of a short period test. The following is a preliminary report of the tests carried out during 1921-1922. Robert Mossberg

Colonel J. Mitchell Moncrieff, C.B.E., M.INST.C.E.(Association of Consulting Engineers) agreed with M. Forchhammer. Before the war, he said, Messrs. Redpath Brown & Co., through their chairman, Sir John Cowan, had approached him with regard to a testing machine they had given to the National Physical Laboratory, and, with regard to certain tests they wished to make, they had this type of construction in their minds. Owing to the war the tests were held up. Tests had been carried out on a few structures, however, and although they were necessarily incomplete, they indicated that there was something to be done in the future in the way of what Mr. Andrews called steelwork reinforced with concrete. To illustrate that, Colonel Moncrieff referred to a test made at the National Physical Laboratory on a 4 in. by 3 in. steel joist covered all round with at least 2 in. of concrete. That made a column something like 7 in. by 6 in., and the column was 16 ft. long, between the points of bearing, including the universal joints at each end. A similar steel joist, without concrete on it, was also tested. The naked joist, which was also 16 ft. long, failed at about 4 tons. The joist coated with concrete carried from 45 to 50 tons. That was worth thinking about. If they could put up the framework of a building, sufficient to carry the mere weight of the structure itself, in concrete, with the addition of tension members, as M. Forchhammer had said, think of the saving in staging! If they could make the bones of the structure carry the flesh until that flesh had sufficient strength in it to act, there was something to be thought about.

IN the design of steel frame buildings it is usual to adopt a “factor of safety” of four, and many people think that this means that four times the ordinary load upon the building would cause failure. This is, however, by no means the case, and it is very difficult to say how many times the ordinary load upon the building would cause failure. Fortunately failures in practice are extremely rare-the author does not remember seeing particulars of a single failure during the past twenty years-and we therefore are unable to learn much as to the actual strength of steel frame buildings from an analysis of the loads and stresses in a building that has failed. Ewart S. Andrews

ALTHOUGH the shattered and dangerous condition of the South Nave wall of Tintern Abbey had led to its condemnation by former custodians in the interests of public safety, H.M. Office of Works Historic Buildings Branch arrested the work of demolition when the ancient structure was placed under its control.