552

In conclusion, then, the only truly “hard data” relative to the CO2 issue indicate that there is no reason to expect any significant change in climate as the atmospheric CO2 content continues to rise in the days ahead, but there is every reason to expect tremendous biological benefits. With this perspective, we can thus face the future with hope and enthusiasm.

S.B. IDS0 (Phoenix, Ariz.)

Electronic Surveying in Practice. Simo H. Laurila. Wiley-Interscience, Chi- Chester, 1983, 380 pp., &tg. 35.75 (hard cover).

This book is a lucid review of the many aspects of electronic distance measuring (EDM) instruments. It primarily is directed to land surveyors at all experience levels. However, because of the important far-reaching developments in EDM technolo~ in recent years, geophysicists, geologists, and engineers will find this volume informative and useful.

Initial chapters introduce metrication and the “Systeme International” (SI) units of measurement. Computer-assisted conversions are concisely presented so that lengths, angles, and scale factors can be handled with ease.

Errors and survey adjustments are treated next with the cautionary note that accuracy and network precision are always to be considered with respect to the survey “order” or category. Atmospheric and environmental conditions are primary factors in selecting the best methods and instrument for the tasks at hand.

Data reductions are made more simple with the presence of the micro- processor in the field, in the situation of the tachymetric or “total station” instrument. From properly adjusted line lengths, the coordinates of points are computed. Emphasis is placed on solutions from observed distances rather than observed angles. This difference in approach is known as tri- lateration versus triangulation. In this solution, observed distances are used in determining three-dimensional point coordinates directly in space instead of a projection to a two-d~ension~ plane.

Various instruments are described, primarily those being used in land surveying and in construction layouts. An overview is given of hydrographic surveying, including system geometry and instrumentation. Finally, data- processing computer terminology is discussed, with differences in various hardware and software packages compared.

A glossary of terms used in electronics, surveying, and computer tech- nology is very helpful to the uninitiated reader. Practical exercises are given at the ends of most of the fourteen chapters. Six appendices add support to the material presented in the chapters. The eleven page index is quite complete, and references are provided for the benefit of the inquisitive reader.

I found this book to be very well written, although the language of the geodetic surveyor is not initially familiar to everyone. The writing of such a book as this one is an ambitious undertaking because the field is so new and yet so broad. Unfortunately, in a few years there is certain to be an obsolescence of instruments and programs described, but hopefully a book like this one can be revised. Already, advances in the Global Position- ing System (GPS) and Very Long Baseline Interferometry (VLBI) are im- proving the figures given in this book. However, such changes are to be expected, and the surveying principles are the important features at hand.

I thoroughly recommend this book to be read by practicing surveyors, engineers, and earth scientists.

JOHNS S. SUMNER (Tucson, Ark)