KNOWLEDGE OF COUNTRY. 57 



hemisphere and the shortest in the northern, and when it is its farthest north it is just 

 the opposite. 



The time of the rising of the sun on the shortest day is in latitude io°, 6.18, in 

 latitude 20°, 6.36, and in latitude 30°, 6.58. 



These times are also those of setting for the longest day. 



At the equinox the sun rises and sets at 6 o'clock. For other times of the 

 year they can be worked out from the declination as they vary in proportion. 



If we take 6 o'clock for sunrise in the tropics we shall not be far out. 



So we have, with the sun vertically over our latitude : 6 o'clock, sunrise. 



7, o'clock when the sun is a little more than the breadth of the palm of the hand 

 above the horizon, the arm stretched out to full extent, with the back of the palm 

 towards one. 



8 o'clock, twice this distance above the horizon. 



9 o'clock, when the length of one's shadow is exactly equal to one's height, this 

 can be observed better by setting up a stick. 



10 o'clock, when the shadow is a little longer than half one's height. 



1 1 o'clock, shadow shorter than half one's height. 



12 o'clock, no shadow at all. 

 Reverse this process for the afternoon. 



When the sun is not vertically overhead the shadow is longer the further the sun 

 is north or south. 



A little practice will soon enable one to judge, and if one knows the declination of 

 the sun, a diagram can always be made that will give the length of shadow at a given 

 time. If you have a compass, the reverse of the directions given above to find your 

 bearing by the sun holds good. 



When the sun is a certain bearing, the corresponding time can be worked out. 



To judge the time at night is still simpler. 



If we have a star moving from east to west it is nearly twelve hours from the 

 time of rising to the time of setting, and the half-circle it performs can be split up 

 into fractions of this time. 



A much more accurate method of observing time at night is to watch the 

 revolution of the Southern Cross. It will be nearly twenty-four hours from one time that 

 it is upright till it again assumes this position, so it will revolve through 90° in six hours. 



That is to say, that, if it was standing upright at sunset, it would be lying on its 

 side at midnight, and the portions of this angle can be spHt up into hours. 



If the position of the cross is carefully noticed at sunset, the time can be told 

 with approximate accuracy by observing the amount it has revolved since. 



I 



