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SUMMARYExperiments have been conducted to measure in incompressible flow the local surface -shear stress and the average skin -friction coefficient for a turbulent boundary layer on a smooth , flat plate having zero pressure gradient. The l ocal surface -shear stress was measured by a floatingelement skin -friction balance and also by a calibrated total head tube located on the surface of the test wall. The average skin -friction coefficient was obtained from boundary-layer velocity profiles . The boundarylayer profiles were also used to determine the location of the virtual origin of the turbulent boundary layer. Data were obtained for a range of Reynolds numb ers from 1 million to about 45 million with an attendant change in Mach number from 0 . 11 to 0.32 .The measured local skin -friction coefficients obtained with the floating -element balance agree well with those of Schultz-Grunow and Kempf for Reynolds numbers up to 45 million. The measured average skinfriction coefficients agree with those given by the Schoenherr curve in the ranges of Reynolds numbers from 1 to 3 million and 30 to 45 million. In the range of Reynolds numbers from 3 to 30 million the measured values are less than those predicted by the Schoenherr curve.The results show that the "universal skin -friction constants" proposed by Coles approach asymptotically a constant value at Reynolds numbers exceeding 21 million. Because of the scatter in the aforementioned constants and the limited Reynolds number range of the present investigation, there i s some doubt as to the validity of any turbulent skin-friction law written on the basis of the present results . Hence, no new friction law is proposed .The frictional res istance of a flat plate was calculated by means of the momentum method and also the integrated measured local surface shear . For Reynolds numbers from 14 million to 45 million both methods give about the same resultj whereas at lower values of Reynolds number the momentum method based on velocity profiles uncorrected for the effects of turbulence results in a frictional res istance as much as 4 percent higher than that of the integrated shear .

This paper describes the enhancement project undertaken at British Steel's Teesside Works which enabled the Universal Beam Mill to become the first such mill in the Western World to introduce the use of continuously cast slabs as the feedstock for rolling heavy beams and columns. The change necessitated construction of a new slab reheating furnace, a complete modification of mill rolling practice and involved several engineering developments needed to enable the new process to be successfully integrated within the existing plant. The new process has resulted in significant benefits for the mill's customers and has greatly improved mill performance through a reduction in material yield losses, higher output speeds and improved plant availability.

Design features of a range of machining centres are described. A four-axis horizontal machining centre with a 1 1/2 m diameter table is described in detail. It is fitted with a 60-station tool changer and automatic pallet loading and uses hydrostatic slideway and spindle bearings. The elements of the machine are of modular design and other configurations and sizes of machine can be made from the same modules.

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