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Book Review

“The Physical and Mechanical Properties of New Zealand Woods.” A. R. Entrican, W. C. Ward and J. S. Reid. Government Printer. Price 18s. 6d.

In New Zealand, timber has always been the most important building material. Even the dwindling supply of the better native species and the necessity to substitute for them exotics and natives which would previously have been thought unsuitable has not deflected the industry from its dependence on timber.

This may be partly because alternatives to timber have themselves been in short supply, and partly because our building industry is based on the trade of carpentry. Whatever the reason, we find to-day that we rely on timber for our buildings just as much as ever before, but that we are using species and grades that fifteen years ago would have shocked us. As is so often the case, what is unfamiliar is met with opposition, but as it becomes familiar it is accepted as a matter of course.

However, the result is that we are now using timbers about which many of us know very little. We have not the background of tradition, of successful use over long periods, to guide us in their application and treatment. In the absence of tradition to guide us, our use of any material, if it is to be successful, must be based on thorough knowledge of its nature and characteristics. It is only by knowing their characteristics that we can expect to use the ‘non-traditional’ timbers so as to exploit their good qualities and avoid their weaknesses.

This leads us to scientific approach of analysing the properties of the many useful species; in particular, comparing, tabulating and discussing the results. Then, if the preferred or known kind is not to be used, another can be selected with some confidence in the performance that can be expected.

The book under review makes such a scientific approach and is authoritative in the best sense of the term. Its importance is suggested in the following quotation from the first page: ‘The report [the book] presents for the first time in the country reliable and authoritative data—comparable with overseas data—upon the fundamental physical and mechanical properties of its woods.’ In other words, we have never before had available fully reliable information on the properties of our timbers, and have never been able so fully to compare them with the timbers of other countries. In reading the book, your reviewer was first disappointed by the limited scope covered and the absence of definite recommendations on the use of particular timbers for specific purposes. Later he became more impressed with the thoroughness of the survey and the avoidance of generalisation. It is true that all the test figures are based on small clear page 70 specimens and that warning is given that a multitude of factors make these unsuitable for use as a basis for design, but all the factors involved are clearly set out and discussed so that an understanding is reached that is much more valuable than an empirical figure.

This is the book of the scientist who carefully analyses the problem but only states his conclusions when he has eliminated all the unknowns. Those of us who use materials in designing buildings must take decisions on the basis of sound judgment, something less than certainty. Such judgment is not, however, as reliable as it should be if it is not based upon as much knowledge as is available. The role of this book is to provide us with the knowledge on which to base our judgment, and we are promised further works of a comparable nature on other aspects of the problem.

Those who want to use timber in such a way that it will give its best should read this book and retain it for reference, but they must not expect ready-made answers to everyday problems; in fact, it will seldom give a ready-made answer to any problem at all.