66 THE BOOK OF NATURE STUDY 



evening, and to make up he would have to keep them burning 

 twelve minutes longer in the early morning. (This, of course, is due 

 to the fact that Edinburgh is west of London, a point which would 

 naturally come up later.) At the Nature Study stage one does not 

 want to go into the question of equinoxes, or even to mention the 

 word, unless it is already known to the class, but the occurrence 

 of equal days and nights in March and September, and the fact 

 that there is a difference between the times of sunset and sunrise 

 in places in a different longitude is an important point. In 

 September the same points are, of course, to be observed that 

 night and day are of the same length in the two towns, but that 

 in London the sun rises earlier and sets earlier than it does in 

 Edinburgh. (The reason, as before, is the westerly position of 

 Edinburgh as compared with London.) 



The solstices show, of course, even more important points. 

 In June the sun rises earlier in Edinburgh and sets later, our 

 motorist there gains an hour's daylight as compared with his 

 London friend, but if he motors all the year round he loses the hour 

 in winter, for in December his lamps must burn for an hour longer 

 than they need to do in London. If we took figures for Aberdeen 

 or Shetland, we should find that the nights get longer and longer 

 in winter as we go north, and shorter and shorter in summer. 

 Carry this on in imagination, suppose we travel on and on into the 

 Arctic, what do we find ? Lead up in some such way to the long 

 Arctic night and the long Arctic day. 



In this way, without formal lessons, without any indications 

 of the difficult problems involved, taking as the means of approach 

 the simple facts of everyday life, we arrive at quite a number of 

 important points, which should be checked by simple direct observa- 

 tions. We know that day and night vary in length throughout 

 the year, that the longest days are those which immediately precede 

 and follow 2ist June, and the shortest days those which precede 

 and follow 22nd December. (Note that it is not strictly accurate to 

 say, as is often done, that 2ist June is the longest and 22nd Decem- 

 ber the shortest day ; as the figures show, there is very little 

 difference in a group of days round the actual turning-points.) 

 We know further that at the end of March and the end of 

 September the days and nights are of equal length. We have tried 



