For many years now, architect-engineer collaboration has been normal practice in the building industry, and for many years the need for such collaboration and the form it should take have been the subject of innumerable papers and discussions in a general sort of way. But there is hardly a general way. Each case is different according to the nature of the job and the personalities involved. When every speaker or author speaks in general terms but has his own personal experiences in mind, misunderstandings are likely to arise.73. I have often expressed the opinion that the many papers written about the design and execution of various jobs would gain in interest and usefulness to the reader if they set out to explain not only how the job was designed and constructed, but why this design was chosen, how it was arrived at, what alternative solutions were considered and rejected, and why, what snags were encountered in the execution and whether the author's experience had given him any ideas for improving the design.74. It follows that if the job has grown out of a dialogue between client, architect and engineer, etc. it would be relevant to record such dialogue or trialogue. That this is very rarely done is understandable, for it is difficult and a somewhat dangerous thing to do-difficult because accurate reporting is difficult, architects or engineers cannot be expected to make notes in the heat of the battle, and trusting to memory is not very safe. It is dangerous because no two people will give the same account of an event in which both took part, and this could lead to undesirable arguments. Nevertheless, it would be useful, because it would throw some light on the different modes of architect-designer collaboration, and could thus further the understanding of the different points of view of architect and engineer.75. One might say that structural engineers are concerned with economic stability and durability and architects with functional delight. The engineer deals with materials and forces of nature; in other words with facts which are not susceptible to persuasion, but demand invention firmly linked to accurate observation and logical deduction. Architecture in its narrow sense results from the manipulation of forms and spaces to create an environment in which man can move and live happily. The architect therefore must study man, his needs and his sensibilities, and he has no firm laws to guide him, only his own sensibility and imagination, which is therefore given free rein. The engineer makes models and prototypes to test their stability; the architect makes models to look at them and study his own reaction, or to impress or persuade clients. He needs to put his architectural vision across. If he presumes to tell people how they should live and what they should like, he must make them see things his way. Hence the need for beautiful models and seductive perspectives, for charm and salesmanship. The engineer has no such worries. Stability is desired by all and anyway not influenced by persuasion.76. It is ...