STUDY OF PHYSICS IN SECONDARY SCHOOLS. 159 



of a central and international observatory '? The place might be the 

 common property of all the civilized nations which might agree to its 

 acquisition ; for, we repeat, it must be neutral ground, a position inde- 

 pendent of all political power, and under guarantee of all the states of 

 the civilized world. The 180th degree would traverse Cape Prince of 

 Wales, where it projects into Behring Strait, and this and the island 

 of Unalashka in the Aleutian Archipelago are the only points where it 

 would touch land. The United States, following the example of Italy, 

 might cede to the republic of science this cape or a part of Unalashka, 

 to be the site of an observatory in correlation with that of Levanzo. 



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THE STUDY OF PHYSICS IN THE SECONDARY 



SCHOOLS. 



By JOHN TKOWBKIDGE, 



AS9ISTANT PROFESSOR OF PHYSICS IN HARVARD UNIVERSITY. 



PHYSICS is a comprehensive term for the laws of the physical 

 universe, and is gradually superseding the old term natural phi- 

 losophy which held together in a disconnected manner various facts in 

 mechanics, light, heat, sound, electricity, and magnetism. Under the 

 head of Natural Philosophy most of us were taught that a body fall- 

 ing from the vertex of an inclined plane acquires the same velocity 

 as it would if it rolled down the plane. A considerable knowledge 

 of mathematics was required to prove this fact, and the youthful 

 mind could hardly see the bearing of it when it was demonstrated. 

 We were shown what we learned to call the falling machine of At- 

 wood, which proved simple laws with such ponderousness of structure 

 and complexity of appliances that even the name of the machine made 

 more impression upon the memory than the laws of which it was the 

 servant. The brightest boys could prove that the square of the ve- 

 locity of a falling body was equal to twice the acceleration of gravity 

 multiplied by the height through which it had fallen, and the rest of 

 us mutely followed the rule, and substituted in a formula which was 

 forgotten as soon as the exigencies of school life were over. We also 

 carried away vague recollections of a pump which worked by means 

 of a curiously constructed valve. We had forgotten whether the cen- 

 ter of gravity is where the center of pressure is applied, or where 

 specific gravity exerts itself. We remembered a tuning-fork, an elec- 

 trical machine, and a big electro-magnet which lifted the smallest boy 

 in school, and that was all that we remembered of natural philosophy. 

 At that very age most of us, if not all, were curious about air and 

 water, the motions of the earth and the moon, the light of the stars, 



