THE HEAVENS IN OCTOBER. the greatest and least altitude in minutes of arc; so that it would then be easy to advance to the right In his position during the day would complicate mat ters. But by making observations for a second day the amount and direction of the drift could be deter mined; for the sun's altitude (still corrected for changes of declination) would be greater in the direc tion of the drift and less in the opposite -direction than on the previous day by the amount of the drift. The explorer would then have all the information necessary for his purpose. One other point may be mentioned. The sun's alti tude must of course always be corrected for refraction practically the same all day long the refraction will be constant (except changes due to weather condi tions which would probably be very small). The ob server's position and drift which are determined from differences of the observed altitudes will therefore be practically independent of the refraction corrections If the conditions of observation were as good as re observer of moderate capacity with portable instru ments (sextant artificial horizon and chronometer) should be able from two days' observations to find both his position and rate of drift With an uncer conditions at the north pole everything would depend on the experience and skill of the observer; but in any case he could fix his position with an error which maps of the polar regions. THE ELEAVENS. Our map shows the aspect of the evening skies; and shows to at a glance how dull the southern and eastern skies would be were not Mars and Saturn there to brighten them. The most prominent eonstellation there is Pegasus which 'lies high up south and east of the zenith. It may be instantly recognized by the Great Square about 15 deg. on a side composed of second-magni of the principal landmarks of the sky for the beginner four corners now belongs to Andromeda; but it was slice grouped with the other three and evidence of this still remains for th
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