Attention is given in this review to water quality as it affects the unit operations of water purification. Physical criteria on which selection of unit operations may be based are put forward. The suggestion is made that the jar or similar tests be carried out by engineers to determine the nature of the orthokinetic flocculation to be applied. Some aspects of chemical dosing and dispersion are also dealt with.
Shrinkage and creep measurements in laboratory tests may be misleading unless due account is taken of the moisture content and dimensions of laboratory specimen and prototype. A method of estimating moisture losses in concrete units of various dimensions is given and the corresponding orders of difference in shrinkage are indicated.
The article on 'Engineering in the South African Lighthouse Service, which appeared in the November, 1969, issue of the Transactions was delivered as an informal paper by a visitor, Mr. H. A. Williams, Lighthouse Engineer of the South African Railways, at a meeting of the Railways and Harbours Division, held at Kelvin House on the 12th August, 1969. Thanks are due to the Chief Electrical Engineer of the South African Railways for permission to publish this paper. The article was not written by J. L. Grossert as published.