10 THE NA 1 URE-STUDY R^'lEW [6:1-Jan., 1910 



building. Each motion having- proceeded without being in any 

 wise affected by the other. Your path of descent will be a 

 curve, because the horizontal motion is uniform, while the ver- 

 tical motion was accelerated — and hence the second law. 



3. Suppose you attempt to throw a heavy weight, you 

 learn by experience that you must brace yourself to prevent 

 the weight from throwing you backward. For every action 

 there is a reaction and the fact that these are equal is interest- 

 ing and entirely acceptable to the pupil upon so good authority 

 as either the text-book or the teacher. Physical nature study 

 stands most in need of readable books, books fuU of information 

 about every day experiences. The fact that many writers are 

 applying their literary art in the service of biological nature- 

 study is the chief reason why it occupies so largely the atten- 

 tion of pupils and teachers. Physical nature-study will never 

 secure much attention in school so long as we cling to the idea 

 that it must get on without books and that teachers and pupils 

 must evolve it wholly from objects. 



We have the richest subject in the whole school curriculum. 

 It lies nearest to the hearts of the pupils. It has in it the great- 

 est possibilities of furnishing both information and training. It 

 simply remains for those who can— to do their duty. 



THE SILO 



By JOHN F. WOODHULL, Ph.D., Professor of Physical Science, Teachers College, 

 Columbia University 



In proposing this topic for nature-study I have merely 

 presented the facts to be taught and said nothing about the 

 method of presentation. It would be my idea to expand each 

 one of the topics mentioned in the preceding paper (read at the 

 Boston meeting), or others according to the locality, some- 

 what after the manner of this' one on the silo. 



Cows need green food, but it is impossible for them to 

 have it for more than half the year unless we preserve it in 

 some way. For our own food in winter we have many farm 

 products preserved by drying, by canning and by pickling. 

 For the cattle, also, we have farm products preserved for win- 

 ter by drying, as, for example, hay; and in the case of the silo 

 we preserve green food by a process much like canning in its 

 results. 



