wrote that since the initiation of the work described in the Paper more information on the rate at which concrete dried had been obtained at the Central Electricity Research Laboratories, Leatherhead. Moisture gauges, similar to those mentioned, had been placed in two large concrete structures, one being the biological shield at a nuclear power station, the other a 6 ft dia., 7 ft block of concrete in the laboratory. Readings from these gauges had been taken for over 5 years at ambient temperatures and for 13 years at higher temperatures. Fig. 12 gave a plot of the moisture gradients obtained and this indicated that, even after 5 years, the depth to which significant drying expressed as loss of evaporable water had occurred was not greater than 2 ft. These results were obtained from the difference between an active gauge and a sealed control gauge kept under the same temperature conditions for the same period. It had been found that the sealed gauges indicated an apparent moisture loss of about t% per year (expressed as the dry weight of the gauge). Quite possibly the dryingout referred to in § 44 was this 'loss' and the actual reduction in the moisture content of the concrete was much less. Fig. 12 were under ambient temperature conditions (16" k4"C). If the temperature was increased, the rate of drying increased considerably. Fig. 13 showed the effect on the moisture loss 3 in. from the surface of 5 year old concrete when the temperature was raised from an average of 20°C to an average of 36°C. Dr B. Mayfield (Civil Engineering Department, University of Nottingham) suggested that from 5 95 et seq., it would appear that the future of concrete turbo-blocks was in the balance and that one of the principal reasons for this move away from the Appendix stated that low-tuned concrete blocks 'would involve an unusual degree of use of concrete was because of the 'uncertainty as to the value of E (dynamic)'. The concrete quality control and the most accurate determination of elastic constants '. 107. The results shown in

Consulting Engineers I shall make my comments from the point of view of a customer who has used the Pilemaster.87. About 18 months ago my firm was responsible to the Ministry of Transport for the reinstatement of two short lengths of river wall at Wisbech. The design finally adopted was steel sheet piling and the Pilemaster was used to install the piles.88. Frodingham No. 4 N piles, 55 ft long were required which had to penetrate between 30 ft and 40 ft into sandy silt. The site was virtually in the town centre and there was a great mass of very old property immediately adjoining the works, some of it being listed as of historic interest. Consequently, when our thoughts turned towards using sheet piling, having regard to noise and vibration the possibility of using the Pilemaster was attractive.89. However, the site had three potentially serious obstacles. First, the adjoining lengths of the river showed ample evidence of earlier structures and we anticipated a lot of timber and stone debris in the upper layers. Secondly, whilst the River Board had been very co-operative and most helpful in allowing us to come forward into the river with our new work, they had no choice but to insist that we put our piles to the same batter as the existing piles. They could not let us have vertical piles. Thirdly, over the second length of wall, the raking piles had to follow a curved line in plan, so we were setting quite a task for sheet piling. 90.Because of these difficulties we thought that a full-scale test was desirable before committing ourselves to the Pilemaster, and in February 1967 the Ministry of Transport arranged for the purchase of a panel of eight piles to be pushed down byPilemaster. As this was completely successful, the project went forward to tender with the Pilemaster specified. 91. The job was completed without undue incident. As the Authors mentioned, we did have to resort to percussive driving on several occasions and it was very noticeable that every time the hammer came on, the Contractors' telephone began to ring with calls from a wide area around Wisbech, but these complaints stopped as soon as the hammering stopped. 92.In the first length of wall we found that the first pile in each new panel refused after about 15 ft penetration and had to be hammered. We never really established why, but two contributory reasons might have been, first, that we had female clutches leading and the outstanding clutch of the previous panel may well have become clogged; also there was a definite tendency for the piles to lean in the line of driving, so that if a panel finished with a slight lean and we attempted to keep the next one vertical, the connecting pile may well have acted as a wedge.93. In the second half of the job we arranged for male clutches to lead, and took greater care to keep the piles vertical, and the job went more expeditiously. Also we introduced a modified form of Pilemaster, so it is not possible to identify the cause of our previous difficulty nor what effected the cure. 94. The modified form of...

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The Author, in introducing his Paper,? remarked that the treatment of rate fixing and the settling of claims were aspects in civil engineering contracts which did not appear to have been adequately dealt with in recent times by the Institution.62. The first question that came to his mind was why was this not a matter suitably covered in standard publications. An examination of the subject, showed that the answer to this question was relatively simple.63. Until the beginning of the second world war, the power of the engineer appeared to have been substantially greater than it was at the present, particularly in the financial sphere. It was indeed a relatively simple matter for the engineer and the contractor to meet at the conclusion of any project and to settle first the outstanding rates and then to settle the claim all in a short discussion. This was a satisfactory way in which to deal with the matter, the assumption being that the two men as heads of their respective firms representing the engineer and the contractor, were men of substance. It also presupposes that the engineer was a man of integrity and vision: he would have to ensure in these negotiations that the employer and contractor each were fairly treated. In this way a quick and satisfactory form of justice appeared to have been effected. 64. In the last two decades, however, with the advent of large nationalized bodies employing their own engineering staffs, the old fashioned method has been found wanting for a variety of reasons. The employer, on his part was naturally conscious that he was dealing with public money and that everything had to be properly accounted for: just as important it must be seen to be properly accounted for. The contractor, on his part appeared to have a tendency with regard to any difficulty to try and evoke the letter rather than the spirit of the contract conditions in general, and the bill of quantities in particular, As to the engineer, it was perhaps more difficult to comment on him, apart from the remarks the Author had already made regarding his diminished power. The engineer seemed to have moved with the times, rather than try in any way to dictate the change in the state of affairs; this might be considered to be a little regrettable on his part.

The C.E.G.B. are installing single shaft turbo-generators of 500 and 660 MW with solid coupled shafts. It is important to assess the extent to which the operation of these large machines might be affected by changes in alignment resulting from differential movements in the turbo-generator blocks. The paper sets out the development of turbo-blocks against the evolution of turbo-generators and associated plant; and discusses the problems which have emerged as a result. The authors investigated 12 existing reinforced concrete turbo-blocks in the 120-200 MW range to establish the extent and cause of differential movements in the concrete and their resulting effects on the machine. Level measurements were taken over a period of about three years on the machine floors and basements of these blocks. These readings were correlated with changes in concrete temperature, moisture content and variations in ambient conditions. Conclusions are drawn from the investigation which can affect the design and construction of concrete turbo-blocks and particularly certain procedures for machine alignment. The continued investigation on the 500/660 MW blocks now under construction is described, as well as methods adopted for the better distribution of heat in the turbo-blocks. Current procedures for design and construction of turbo-blocks are reviewed, relative merits of concrete and steel blocks compared, and the changing roles of plant manufacturer, civil engineer and block contractor/manufacturer considered. The tentative views formed by the authors from this study, from continental sources and from their discussions with power station superintendents and staff are submitted for discussion.