Abstract
THIS planisphere measures 5½ in. by 5 in. and can be carried in the pocket without the slightest inconvenience. It shows how the stars appear for each month on any selected day or hour to an observer in lat. 50° N. and also in lat. 35° S. On the rotating disk each month is divided into four portions, the first division being on the first of the month ; and seven-day intervals are adopted in all cases except at the end of the months, when the arrangement necessitates intervals of nine or ten days. It is very easy interpolating and setting the planisphere for the selected day and also for the time of the night, intervals of one hour being used. As the space between successive hours is six-tenths of an inch, sufficient accuracy for fractions of an hour can be obtained. The names of the important navigation stars are in capitals and numbers are attached to other stars which the navigator may wish to use, a key to these numbers being printed on the back of the mask which covers the star disk. Directions for using the planisphere are supplied ; it will prove a very useful equipment for the air navigator.
The Pocket Planisphere
Francis
Chichester
By. Pp. 4. (London: George Allen and Unwin, Ltd., 1943.) 2s. 6d. net.
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D., M. The Pocket Planisphere. Nature 152, 63 (1943). https://doi.org/10.1038/152063c0
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DOI: https://doi.org/10.1038/152063c0
