826 Home Nature-Study Course. 



Another excellent observation lesson for teaching the fact that the 

 sun travels farther south in the winter is to measure the shadow of a tree 

 on the school ground at noonday once a month during the school year. 

 The length of the tree shadow can be measured from the base of the tree 

 trunk and a memorandum made of it. 



Facts for Teachers. — The most obvious benefits which we receive from the sun 

 are light and warmth, and all life upon our globe is dependent upon light and heat. 

 We get the least heat from the sun directly after it rises or just before it sets, 

 and we get the most heat from the sun at noon when it is most nearly over our 

 heads. This is true, although the hottest part of the day may be at three o'clock 

 in the afternoon, but this is because of the effect of the atmosphere blanket and 

 not because the sun gives us more heat at that time. Of course, the sun is equally 

 hot at all hours of the day and all days of the year; the reason why we do not get 

 the same amount of heat constantly is because of our position in relation to it, 

 and the reason why we get the least heat just after sunrise and just before sunset 

 is because the rays of the sun strike us more obliquely and are obliged to pass 

 through a much greater distance of our atmosphere. Question 4 the children 

 should answer preferably by observation, but if not possible by observation through 

 consulting the almanac. This is merely to call their attention to the lengthening 

 days. It would be well to continue this lesson through September, November and 

 December, so that they shall notice more closely the fact of the shortening of the 

 days during the autumn. The shortest day of this year, as computed from a cur- 

 rent almanac, is the 22d of December, and it is 9 hours and 14 minutes; the longest 

 day of the year is the 226. of June, and it is 15 hours and 6 minutes. On the 

 longest dc / of the year the sun has reached the farthest point north and is, there- 

 fore, most nearly above us at midda_. . On the other hand, on the shortest day 

 of the year it reaches its farthest point south and is, therefore, farther from the 

 point directly above us at midday than during any other day of the year. A very 

 good lesson for the children to read that will make these facts clear to th::n is the 

 Supplement to the Home Nature-study Course by John W. Spencer, New Series. 

 Volume III, April-May, 1907. This lucid explanation written in Uncle John's best 

 style is, in the editor's opinion, a most valuable contribution to the study of the sun. 



The observations suggested in question No. 9 should be carried out by the pupils, 

 so that they may see for themselves how much farther south the sun rises and sets 

 in the winter than in the spring. Of course, our shortest day of the year comes 

 when the sun is farthest south and our longest day when the sun reaches its farthest 

 northern point. The sun rises due east and sets due west at the time of the 

 autumnal and of the spring equinox. Answers to question No. 12 may be made 

 most entertaining by simply multiplying the weight of any object by 27^. 



References. — Any standard text book on astronomy, like, Newcomb 

 & Holden, Sharpless & Phillips, Todd or Proctor. For the pupils' essays 

 "Star Land," Ball; "The Earth and Sky," Holden; "Stories of Star 

 Land," Proctor, are very good. 



