206 



JSGIENCE. 



[N. S. Vol. VIII. No. 190. 



practically to that of a school for civil en- 

 gineers. 



Of the great number of technical schools 

 which have sprung up since 1850 there is 

 no need to speak. But the interest in sci- 

 ence has gradually passed far beyond 

 the mere interest in its applications. 



The striking features of the last twenty 

 years have been the spread of science teach- 

 ing by laboratory methods in the secondary 

 schools, and the growth of university in- 

 struction in science, as distinguished from 

 technical. The noble gift of Johns Hop- 

 kins, and its wise administration, began 

 the latter movement, which resulted in the 

 establishment of graduate schools all over 

 the country. The State universities, with 

 their large resources, were, in some parts of 

 the land, great aids in this work, though in 

 others they kept more closely in touch with 

 the technical side, as is very natural with 

 institutions supported by the public at 

 large. 



The growing fashion among students, of 

 completing their years of study in Germany, 

 has had a most important effect. The in- 

 structors in science in our colleges are drawn 

 more and more from those who have added 

 German training to that of their native 

 country, and as a result the ideals in these 

 institutions are approximating to the Ger- 

 man ideals. 



Ability in the direction of original re- 

 search is in some places the first quality 

 looked for in a student or required of an 

 instructor, and the modern tendencies to- 

 ward extreme specialization and hasty pub- 

 lication are natural results. 



So far the movement has undoubtedly 

 been productive of good to the whole edu- 

 cational system of this country. There 

 has been an arousing, an awakening, in 

 educational ideas and methods, not in sci- 

 ence only, but in all other subjects, that is 

 little less than marvellous to him who can 

 look back five and twenty years. Whether, 



after our American fashion, the pendulum 

 may swing too far, and the movement 

 bring with it the difficulties which always 

 attend exaggerations, it is too early yet to 

 say, but, so far as we have gone at present, 

 not only teachers of science, but all teach- 

 ers, may join, in spirit at least, with the 

 meeting at Boston, which really celebrates 

 the beginnings, not merely of a scientific 

 association, but of a great scientific and 

 educational movement, of which the Asso- 

 ciation forms but a part. 



Frank P. Whitmai^^. 



EYDRAULIC ILLUSTRATION OF THE 

 WEEATESTONE BRIDGE. 



Although it is undesirable to push the 

 analogy between the electric current and 

 the flow of water too far, or to get the idea 

 of an actual current too firmly established 

 in the student's mind, still a hydraulic il- 

 lustration is often useful to point out how 

 the results may follow. 



To show the action of the Wheatestone 

 bridge by flowing water is usually compli- 

 cated by the efiects of gravity, and illus- 

 trates the conditions of pressure rather than 

 those of resistance to flow. Moreover, the 

 question of the galvanometer is a trouble- 

 some one, inasmuch as most devices require 

 such a flow of water as to interfere with 

 the bridge effects which it is desired to 

 bring out. 



The arrangement described below has 

 proved quite satisfactory in showing the 

 simpler resistance effects in the bridge, but 

 especially useful in making clear the effects 

 of capacity and self-induction, and how the 

 two may be balanced and compared. 



The accompanying sketch is taken from 

 a simple home-made bridge which was con- 

 structed as an experiment. Upon a board 

 about 30 X 50 X 4 cm. are fastened four glass 

 2"s of about 5 mm. inside diameter. Two 

 of these T's have their side projections 



