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SUNCLOCKS - Paper Sundials to Make and Use.
JVT Publications, 5549 Camus Rd, Carson City, NV 89701, USA, ISBN 1-893812-51-0, $12.95
This book is a very useful introduction to sundials. It explains the basics of dialling, and gives a glossary of terms. It has a full explanation of the differences between sun time and clock time, with illustrations from the USA. There are instructions for how to find true north, and thus set up a sundial. The main part of the book consists of paper models of horizontal, vertical, and equatorial sundials to cut out and make.
For horizontal and vertical dials, there are 8 different models, calculated for latitudes from 26 deg. To 48 deg. which covers the whole of the contiguous United States. The models are printed on thick paper, with clear instructions for how to cut and assemble them. The design for each latitude is slightly different, and there are some ornamental features, so that they are suitable for colouring in. The equatorial dial models have 8 different bases using the same dial plate. This approach means that there is no need for any calculation; the user just selects the sheet for the nearest latitude, cuts it out and assembles it.
As a quick, uncomplicated way of getting acquainted with the basics of dialling, this book would be hard to beat. While aimed specially at 10 to 14-year olds, the book would be equally useful to adults newly interested in sundials.
It is to be hoped that this book will be so successful that it will be possible in the next edition to introduce sheets for say 51 and 54 degrees, so that it would be suitable for users in Northern Europe as well as those south of the latitude of Paris. It would be helpful to users to have a list of further sources so that their interest, once kindled, could be developed further. .
The author presents step by step instructions, with good, clear diagrams, for making a sundial. He then goes on to use the dial as a teaching aid to explain the earth's rotation and the system of time zones.
The title is rather off-putting as no sundial is "clock accurate" and all sundials should be "customized". In fact, the author contradicts the title in the introduction by saying that the sundial, when constructed, will be "always close to clock time", the usual correction has to be made for the equation of time. The method described for marking the hour lines avoids the necessity to make a correction for longitude by setting up the dial, noting the clock-time, allowing for the equation of time, and drawing along the edge of the shadow. The author then goes on to explain the system of time zones by suggesting that the dial be transported 100 miles East or West, and noting that the time is no longer "clock accurate".
The very idea of using a watch to make a sundial would offend many serious diallists, but I can see the use of this sundials as a teaching aid and, it should be borne in mind that this is a book for American children, not for members of the British Sundial Society. The difference between standard time and local time can be considerably greater in America than we are used to contending with in Great Britain.
The method used for drawing the hour lines in unlikely to work as well in practice as the author suggests because the edges of shadows are always diffuse.
The photograph of page 4 is confusing as it appears at first sight to show a vertical dial with very strange hour lines. the photograph on the back cover of the author holding the dial is clearer.
This little book of 58 A5 pages is not aimed at classroom teaching, but at children with an interest in science out of school, and, as such, will certainly stimulate interest in dialing.
[Reviewed by Jane Walker]
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