3 o2 THE POPULAR SCIENCE MONTHLY. 



lar books were kept by them for recording observations. They kept 

 account of the phases and the corresponding relative positions of the 

 sun, moon, and earth. This led to a very interesting discussion as to 

 what makes the moon shine. In the course of this, they drew dia- 

 grams and experimented with the ball and light. They detected the 

 earth-shine, and settled its cause for themselves ; found out that the 

 moon moves round the earth, and noted the time ; noted the hours of 

 rising ; noted the various constellations through which the moon takes 

 its path ; and noted the effect of their situation on the moon's time of 

 lising. After these points had been settled, I asked them, had they 

 ever seen the moon show more than one face. As this called attention 

 to the fact that the moon always shows (substantially) the same face, 

 the cause was discussed. To settle it, a girl stood in the middle of the 

 room and another walked round, facing her all the time. They finally 

 settled for themselves that the moon revolves once on its axis while 

 it moves once round the earth. I gave them no further help than 

 the question I have just stated. I have not yet had pupils trace the 

 moon's path and that of the sun so accurately as to discover the nodes, 

 but I certainly shall try to do so, and to have the retrograde motion of 

 the nodes detected ; the time (approximate) of their revolution. I 

 shall pass over nothing that ordinary eyes can see, ordinary minds 

 reason out. 



The study of planets affords delightful work. Some of my pupils 

 have studied Mercury with great interest, finding that his orbit is 

 within that of the earth and of Venus ; finding the direction of his 

 motion round the sun, and the period. The study of Mars is in the 

 highest degree profitable, and so is that of Venus. The young folks 

 can readily discover the retrograde motions, and, with the simple sug- 

 gestion that the apparent retrograde may result from the changed 

 position from which we view the planet, may find the relative positions 

 and detect the cause. 



I occasionally report to my young astronomers a little of the testi- 

 mony of other persons. Thus, in discussing the cause of the moon's 

 light, I told them of stars occulted by the dark part of the moon. In 

 doing so, I always wait until they have exhausted the evidence of 

 their own senses ; and I am specially careful to distinguish between 

 the two kinds of testimony. It leads, with older girls, into some very 

 interesting discussions as to the value of other people's evidence. 



Sometimes some of the girls begin to guess. I always take special 

 care (in a good-natured way) that guessers shall come to shame. I 

 endeavor to make them as accurate as possible, allowing the evidence 

 to prove just what it ought, and no more. 



My pupils have been so much interested in astronomy, that their 

 talk about it has brought to me a good many persons who wish to sell 

 me some sort of apparatus for illustrating the motions of the solar 

 system or some part of it. I do not much believe in these contriv- 



