August 26, 1898.] 



SCIENCE. 



265 



railway projects. The statement of accounts 

 showed a balance in hand of £191 on an income 

 of £1,177. 



The Elektrische Zeitung publishes in its issues 

 for July a long article by Dr. Zicliler on teleg- 

 raphy by means of ultra-violet light. According 

 to the abstract in the Electrical World, it appears 

 that he proposes a new system of wireless tel- 

 egraphy, the chief object of which is to over- 

 come the objection to the electromagnetic wave 

 system which lies in the fact that these waves 

 are distributed in all directions, and cannot be 

 concentrated in one direction, all methods for 

 doing this having apparently failed. The prin- 

 ciple of his method, which it seems he has tried 

 with success, is based on an observation first 

 made by Hertz — namely, that light rays of 

 short-wave length, especially the ultra-violet 

 rays, have the property of promoting electric 

 discharges — and his receiver is based on this 

 fact. The transmitter consists of an arc light, 

 the rays of which are condensed with lenses or 

 reflectors into the direction in which they are to 

 be sent, and at the receiving end the ultra- 

 violet rays promote the discharge in a spark 

 gap, which discharge will give rise to electric 

 waves, which operate a coherer and through 

 this a bell, a telephone or an ink writer ; the 

 apparatus is shown by means of diagrams. The 

 condensing lens on the transmitter must be 

 made of quartz, and not of glass, as the former 

 will transmit the ultra-violet rays and the glass 

 will not ; these ultra-violet rays are shut off in- 

 termittently as desired, by means of a glass 

 plate, which is moved rapidly in front of the 

 camera like a shutter on an ordinary photo- 

 graphic camera ; the ultra-violet rays will, in 

 this way, be cut off, while there will be no ap- 

 parent effect on the light rays, and for this 

 reason the secrecy of the message will be pre- 

 served ; the ordinary searchlights could be ar- 

 ranged to be used for the transmitter. The re- 

 ceiver consists of a glass tube, one end of which 

 is made of a plate of quartz, so as to allow the 

 ultra-violet rays to enter ; these fall on a small, 

 slanting plate in the tube, and forming one of the 

 electrodes of the spark gap ; 10 mm. from this 

 is the other electrode, in the form of a small 

 ball ; both electrodes are mounted with pla- 

 tinum ; the air in the tube is exhausted to a 



certain degree, or is filled with a rarefied gas ; 

 the electrodes are connected with the secondary 

 of a small induction coil, the knob being the 

 anode and the disc the cathode ; the induction 

 coil need only give a spark of 1 to 2 cm. and 

 should be provided with an adjustible resist- 

 ance for regulating the voltage, so that it will 

 be justinsuflBcient to produce a spark when no 

 rays fall on the gap ; whenever the rays are 

 received a discharge will take place ; a coherer 

 in the immediate neighborhood may be used to 

 produce a call or any other signals. If the 

 signals are merely to be made audible a tele- 

 phone in the discharge circuit is sufficient. He 

 begins the description of the results of a 

 very large number of experiments which 

 he has made, mostly with crude apparatus. 

 He found that platinum was by far the best 

 material for the electrodes, the charge between 

 which is to be effected by the light ; the ques- 

 tion of the best shape of the electrodes was not 

 so easily answered, and no definite results were 

 obtained ; the air surrounding the spark gap of 

 the receiver was exhausted to 200 mm., which 

 gave better results ; the first tests were made at 

 very short distances, and were then increased 

 to 50 meters, at which very satisfactory results 

 were obtained. Some deductions are then made 

 from this data for greater distances, and he 

 shows how much the light must be increased 

 with the distance ; with a 25-ampere lamp pro- 

 vided with a suitable reflector he thinks it will 

 be possible to telegraph in this way to a dis- 

 tance of a number of kilometers ; experiments 

 with greater distances are to be carried out. 



UNIVERSITY AND EDUCATIONAL NEWS. 



The London University Commission Bill has 

 been finally passed both by the House of Com- 

 mons and by the House of Lords, and London 

 will have a teaching university as soon as royal 

 assent has been added. 



Another extremely important educational 

 advance in Great Britain is announced in the 

 introduction of a bill into Parliament by the 

 government reconstructing the entire system of 

 secondary education. There will be a compre- 

 hensive educational department presided over 

 by a Minister of Education. 



