SCIEXCE- G OSSIP. 



CONDUCTED BY JAiJES QUICK. 



Becquerel Rats. — An excellent resume of our 

 present knowledge on the subject of Becquerel 

 rays is given by Oscar M. Stewart in the September 

 issue of the '• Physical Review. - ' The whole his- 

 tory of the subject is well written, and the matter 

 is subdivided so that the different properties of 

 the rays may be treated separately. The theory 

 that Becquerel rays consist of extremely short 

 ultra-violet light waves is now almost abandoned. 

 In the case of the deflectable rays it is entirely 

 dropped, and it is believed that they, like kathode 

 rays, are negatively-charged particles of matter 

 moving at extremely high velocity. Results from 

 other experiments seem to show that the ratio of 

 the atomic electrical charge to the mass of these 

 small particles always remains the same, and that 

 it is probably the velocity of the particle that 

 varies to produce the different effects observed. 

 The difference in penetration of Becquerel rays 

 and kathode rays is then readily explained by a 

 greater velocity for the Becquerel ray particle. 



Wireless Telegraphy. — One of the greatest 

 difficulties in the way of the successful and 

 universal working of wireless telegraphy methods 

 is now apparently being surmounted by Marconi. 

 Hitherto it has not been possible to so tune the 

 receivers that they will only respond to waves of 

 definite wave-lensrths sent from the transmitter. 

 The method employed by Marconi is the process 

 of syntonising the receivers, each to a special 

 wave-tone. The method apparently does not 

 originate with him. but he appears to be the only 

 experimenter who has given such a practical proof 

 of the idea. He has modified his receiving and 

 transmitting appliances so that they will only 

 respond to each other when properly tuned to sym- 

 Tjathy : the isolation of the lines of communication 

 «an therefore be effectively carried out. These 

 latest experiments were made between two sta- 

 tions thirty miles apart : one near Poole, in 

 Dorset, and the other near St. Catherine's, in 

 the Isle of "Wight. The apparatus was so ad- 

 justed that each receiver at one station re- 

 sponded only to its corresponding transmitter 

 at the other. Two operators at St. Catherine's 

 were instructed to send simultaneously two dif- 

 ferent wireless messages to Poole, and without 

 delay or mistake the two were correctly recorded 

 and printed down at the same time in Morse 

 signals on the tapes of the two corresponding 

 receivers at Poole. These receivers were then 

 placed one on top of the other and connected both 

 to the same aerial wire hung from the vertical 

 mast. Two messages were then sent from St. Cathe- 

 rine's, one in English and the other in French. 

 "Without failure each receiver at Poole rolled out 

 its paper tape, the message in English perfect on 

 one, and that in French on the other. Additional 

 experiments were then made in which the vertical 

 wire attached to the mast was replaced by a hollow 



zinc cylinder. No difficulty was experienced in 

 transmitting and receiving isolated messages under 

 these conditions. This great improvement does 

 away with the necessity of the cumbersome tall 

 ma.~t hitherto employed. From the above most 

 successful results it will easily be seen what an 

 immense stride has been made towards the com- 

 plete practical solution of the problem of indepen- 

 dent electric wave telegraphy, in which each 

 wireless circuit can be made as private as one 

 with a wire. 



Simple Relay for Space Telegraphy. — 

 A simple relay for use in Hertzian wave and 

 simiiar experiments has recently been devised. It 

 is constructed somewhat similar to an electric 

 bell. The electro-magnets are arranged hori- 

 zontally, and the vibrator haDgs vertically down 

 by their side. The armature is a heavy one, and 

 is also weighted. It is covered with tissue paper 

 next to the magnet, and, to avoid adhesion as far 

 as possible, the platinum contact-piece is so 

 adjusted that it touches the insulated electrode 

 before the armature touches the magnets. The 

 armature is suspended by means of a German- 

 silver spring, and its normal distance from the 

 magnets is only one millimetre. Exemplifying its 

 sensitiveness, it may be mentioned that the waves 

 from a small Hertzian oscillator, consisting of two 

 straight cylinders 5 cm. long and 1 cm. in 

 diameter, can be detected over a length of thirty 

 or forty metres, and all the Hertzian reflection 

 experiments can be made with it. 



Kew Observatory. — Matters are still proceed- 

 ing in reference to the apprehended magnetic 

 disturbance at Kew due to the proposed electric 

 tramways in that neighbourhood. Another con- 

 ference took place recently between the Board of 

 Trade and representatives of the Royal Society 

 and the London United Tramways Company. The 

 proceedings were private, but it is certainly to be 

 desired that an agreement may soon be arrived at 

 as to the means in which the Tramways Company 

 shall arrange its circuits so as not to affect in any 

 way the work conducted at Kew Observatory. 



Physical Society of London. — At a meeting 

 of the Physical Society on October 26th Dr. Shel- 

 ford Bidwell exhibited some interesting experi- 

 ments illustrating phenomena of vision. " Recurrent 

 vision " was first illustrated. An illuminated vacuum 

 tube rotating about a horizontal axis was seen to 

 be followed, at an angle of about 40°, by a feeble 

 ghost of itself. The same effect was observed in 

 the cases of spots of white, green, and yellow light 

 when these were rotated in a circular path. A 

 spot of red light, however, had no ghost. These 

 phenomena are due principally to the action of 

 violet nerve-fibres. The non-achromatism of the 

 eye was next shown. A six-rayed star, formed by 

 cutting a hole in an opaque screen, was illuminated 

 by a gauze-covered condenser containing an in- 

 candescent lamp. The star was somewhat clearly 

 defined, and no coloured fringes were seen. A 

 luminous haze was, however, observed, being 

 brought about chiefly by the three brightest rays — 

 orange, yellow, and green. If, therefore, these 

 rays are obstructed, coloured fringes can be seen, 

 due to chromatic aberration of the eye-lenses. 

 This was done, and the general hue of the star was 

 seen to be purple. Other experiments illustrating 

 further phenomena of vision were also performed. 



