Dr. D. D. Matthews (Vice-president) had a series of technical questions to put to the author. What did he consider to be the maximum practicable weight to handle on a building site? Fig 3 of the paper showed some hammer head cranes of a type that Dr. Matthews had seen only in Eastern Europe. He was interested to have any data that could be given about the loads these could carry, as well as the speed of lifting.
Concepts of Structures, by William Zuk (New York: Reinhold Publishing Corp., 1963) 9 x 6 in., 79 pp., 48s.
Mr. I. M. Nitkin of the Engineering Laboratory, Cambridge, writes:- 'Professor Neal and Dr. Griffiths have demonstrated quantitatively that the capacity of a redundant truss is not necessarily exhausted upon first buckling. This is a fact not generally understood. It is interesting to note that, for the particular truss considered by the authors, the shape of the load-deformation curve for the strut BD makes very little difference to the ultimate load.'
The paper describes the design and construction of five footbridges similar in design and appearance that have been erected on the Kwinana Freeway near Perth, Western Australia. D.J. Lee
The paper describes detailed microscopic investigations of the extensibility and microcracking of the in-situ concrete in composite beams with precast prestressed concrete members and in-situ reinforced concrete members. The experimental work included the use of mirror extensometer gauges (sensitivity = 0.5 x 10 to the minus 6 strain approximately) to indicate the onset of cracking, and the location and examination of the cracks with a microscope of 100 magnification. R.H. Evans and F.K. Kong