356 



SCIENCE. 



[Vol. IV., No. 88. 



would speedily be replaced by that of the three 

 D's, — drill, drawing, and (a)clroitness. At 

 the close, Mr. J. R. Lowell, the American 

 minister, speaking as an ex-professor of Har- 

 vard, moved a vote of thanks ; which was 

 seconded (in French) by Mr. Buisson, director 

 of primary education in France. Mr. Auguste 

 Couvreur of Belgium supported the motion ; 

 thanking also Lord Carlingford and Mr. Mun- 

 della, the English government representatives 

 of the education department, for their presence 

 there that clay. There were about fifty foreign 

 delegates from twelve countries (including 

 Japan and Brazil), attending this conference, 

 the proceedings of which will be published in 

 the course of the autumn. The conference, 

 after being opened by Lord Rea} T , divided it- 

 self into four sections, which sat simultaneous- 

 ly from ten to one and from two to five for five 

 days ; and we conclude this article with a list 

 of some of the more important subjects on 

 which papers were read and discussed. 1°. 

 The conditions of healthy education ; 2°. In- 

 fant training and teaching ; 3°. Technical 

 teaching of all kinds (b} r Professor Woodward, 

 St. Louis, U.S.A., among others) ; 4°. The 

 methods of teaching the different branches of 

 physical and natural science in elementaiy and 

 other schools ; 5°. The teaching of music ; 

 6°. Museums, libraries, etc. ; 7°. Training of 

 teachers ; 8°. Inspection and examination of 

 schools ; 9°. Organization of elementary edu- 

 cation ; 10°. Organization of intermediate and 

 higher education; 11°. Organization of uni- 

 versit}' education ; 12°. On the teaching of 

 agricultural science. 



William Lant Carpenter. 



RAILWAY-SIGNALS AT THE ELEC- 

 TRICAL EXHIBITION. 



Among the interesting features of the Electrical 

 exhibition are the different systems of automatic 

 electric railway-signals, designed to render collisions 

 and wrecks impossible. One system, already in quite 

 extensive use, is there illustrated in its application to 

 the running of trains on the block system, on both 

 single and double tracks, to tbe approaches of a 

 crossing of two roads at the same grade, and to va- 

 rious combinations of switches and signals, whereby 

 a signal cannot be set so as to ' clear' a train until the 

 switch has first been turned in the proper direction, 

 and by this very motion has automatically unlocked 

 the signal-lever. If through any obstruction or 

 failure in the connections the switch is not thrown 

 clear over to its proper position, the automatic elec- 

 tric unlocking action will not respond, and the sig- 

 nal cannot be turned to let the train proceed. The 



lication to a crossing of two roads at grade is very 

 ingenious. The four approaches are guarded by 

 switches, always left open when not in use; so that a 

 runaway locomotive, or other destructive intruder, 

 would be switched round upon a side curve, out of 

 harm's way, as far as the crossing is concerned; and 

 the signals are locked fast at 'danger' as long as 

 these switches are open. Upon the approach of a 

 train from any of the four directions, it announces 

 itself in the signal-house while still at a considerable 

 distance; and then, if the crossing is clear, and there 

 is no previous announcement from either of the other 

 three directions, the signal-man in his lookout-house 

 turns a lever, which, by pneumatic action, closes the 

 switch for the approaching train. This same lever- 

 motion locks all the other switches open ; so that the 

 man could not, if he would, let any other train ap- 

 proach the crossing till this one had passed. If the 

 switch closes safely, an automatic electric circuit un- 

 locks the danger-signal lever for this one switch. The 

 man then turns it, and then clears the track for the 

 oncoming train, which can thus pass safely without 

 stopping. If trains approach, meanwhile, from other 

 directions,. the danger-signals and open switches — 

 which the signal-man himself cannot unlock till the 

 train has passed the switch beyond the crossing, and 

 automatically unlocked them — prevent any other 

 train from getting to the crossing. 



In running upon the block system, it is so arranged 

 that a train entering upon each section, automati- 

 cally closes there a green warning-signal and a red 

 danger-signal for any following train. As it leaves 

 the section, it automatically signals back, and opens 

 the red danger-signal, but leaves the green warning- 

 signal till it has left the next section, two blocks 

 ahead. The action of a train, then, in leaving one 

 section and entering on another, is to set the two 

 signals there, and to signal back one block to open 

 the red signal, and two blocks to open the green. 

 The engineer of a following train, upon seeing a 

 green signal, will know that a train is somewhere 

 on the section next but one ahead of him, and will 

 run cautiously; and if, upon reaching the next sig- 

 nal, he finds both the green and the red, he must 

 stop till the train ahead has opened the red one. 

 Upon a single-track road a similar set of signals is 

 given, on the other side of the track, for two blocks 

 ahead as well as behind the train. The automatic 

 train-signals are all given through pairs of insulated 

 rails, across which any pair of car-wheels will close 

 an electric circuit; and they are so arranged, that, if 

 the battery fails, the signal goes to danger through 

 the action of gravity, and so remains till the trouble 

 is remedied. This system depends principally, for 

 safety, upon the watchfulness and certainty of the 

 engineer in reading the signals correctly. 



Another company exhibits a system which in some 

 respects is superior to this in avoiding the danger from 

 sleepy or inattentive engineers, or from the difficulty 

 of reading the signals in stormy or foggy weather, and 

 the trouble from batteries giving out or getting weak. 

 Each locomotive carries its own battery in the shape 

 of a dynamo, driven constantly by a small steam-en- 



