34 



NATURE 



[March 15. 1913 



The foregoing' announcement is the preamble 

 preliminary to the time signals. 



At ioh. 44m. os. a series of longs or , 



&c, are transmitted, ceasing at ioh. 44m. 55s.; 

 then there is silence for some seconds, and exactly 

 at ioh. 45m. os. a single "short " is heard. 



A whole minute is then allowed to elapse with 

 no signal at all, but at ioh. 46m. os. a new series 

 of signals is commenced-.. -.. -•• , &c, until 

 ioh. 46m. 55s. is reached, when again there is 

 silence for a lew seconds, and then a short tap at 

 exactly ioh. 47m. os. Another minute of silence 

 is then allowed to pass, and at ioh. 48m. os. 

 a different series of signals is commenced 



, &c, terminating- about ioh. 48m. 



55s., when after a few seconds' silence the single 

 tap that follows indicates exactly ioh. 49m. os. 



Thus it will be observed that the hearer has 

 not only three opportunities of correcting his time- 

 piece, but if by chance he missed the first signal at 

 ioh. 45m. os. he can identify the other minutes 

 by the different signals which precede them. 



' In the case of the German signals transmitted 

 from Norddeich-Wilhelmshaven, at about 12 

 o'clock midday and 10 o'clock in the evening, the 

 procedure is quite different. The first notifica- 

 tion is the transmission of a series of V's thus, 



, &c, to give the hearers a chance to 



tune their instruments to the wave-length in use 

 (about 1750 metres) if not already in adjustment. 



The "call " signal is then sent out, followed 



by the "call signal" of the station transmitting, 

 namely, Norddeich, thus "£" "Jj ")'• The fact 

 that Greenwich mean time is being sent is given 

 in die next signal in the form ~jj[ "" ~z"' 

 where MGZ indicate Mittel Greenwich Zeit. At 



nh. 58m. 38s. the signal or attention is 



repeated, and then follows the following series of 

 signals : 



Commencing at nh. 58m. 46s., a tap is heard 

 at every second until nh. 58m. 50s. is reached; 

 then a short pause is made, and another series of 

 taps from nh. 58m. 56s. to nh. 59m. os. ; again 

 another pause, and a third series from nh. 

 S9m. 6s. to nh. 59m. 10s. Then follows a longer 

 pause, and a similar series of taps is heard for 

 each of the intervals nh. 59m. 36s. to nh. 

 59m. 40s., nh. 59m. 46s. to nh. 59m. 50s., and 

 nh. 59m. 56s. to I2h. om. os. A few seconds 



after the last tap the signal indicating the 



end of transmission is given. 



The above two examples show what very dif- 

 ferent systems are in use for the distribution of 

 time by' radio-telegraphy. They serve further to 

 indicate that unless some international scheme is 

 at once brought into operation, many other 

 different systems may be added. 



The Paris International Conference has thus 

 stepped into the breach at the right moment and 

 brought out a scheme which will be universally 

 adopted and commenced on July 1 of the present 

 vear. 



It is proposed for the international scheme that 

 Greenwich time should be used throughout, and 



NO. 2263, VOL. 91] 



that the time signals should be transmitted at exact 

 hours. It was further arranged that there should 

 be no overlapping, i.e. that no two stations should 

 send out signals at the same hour, and that the 

 same wave-length (about 2500 metres) should be 

 universally adopted. 



A' preliminary list of stations that will be in 

 active operation by July 1 is as follows, and the 

 times at which they will transmit their signals are 

 added : 



Greenwich civil time. 

 Hours 



Paris o (midnight). 



San Fernando (Brazil) 2 



Arlington (U.S.A.) 3 



Manilla 4 (provisionally). 



Mogadiscio (Italian Somaliiand) 4 



Timbuctu ... ... ... ... b 



Paris ... ... ... ... ... 10 



Norddeich-Wilhelmshaven ... 12 (midday). 



San Fernando (Brazil) 16 



Arlington (U.S.A.) 17 



Massowah (Erythrea) ... ... 18 



San Francisco ... ... ... 20 



Xorddeich-YVilhelmshaven ... 22 



Since September 1, 1912, radio-telegraphic time 

 signals have been daily sent out from Choshi, on 

 the eastern shore of Japan. They are transmitted 

 at 9 p.m. Japanese standard time, i.e. at Green- 

 wich noon. This station will no doubt adopt the 

 international scheme. 



An important part of the scheme that is desired, 

 and will ultimately no doubt be accomplished, 

 is that both a day and a night signal can be 

 received at any point on the globe. 



Now as to the method which will be adopted 

 for distributing the exact time at all transmitting 

 stations. 



To make the svstem quite clear, the accom- 

 panying figure (Fig. 1), taken from the report 

 of the conference as recorded in the Comptes 

 rendus (November 4, 1912, No. 19, vol. civ., 

 p. S72), is shown. The reader is supposed to 

 commence the time reckoning from the innermost 

 port inn of the spiral. 



At three minutes before the hour — that is, at 

 any hour at which the signals are intended to 

 distribute the time — the transmitting operator 

 sends out a series of successive similar pre- 

 liminary signals, a repetition of the letter X in 

 Morse -..- -..- -..-> &c. These commence at 

 the beginning of the 57th minute, and con- 

 tinue until 57m. 50s. has been reached. Then, 

 beginning at the 55th second, three longs are 

 given at intervals of one second, each long lasting 

 one second. In the 58th minute a short (lasting 

 for a quarter of a second), preceded by a long 

 commencing two seconds before, heralds every 

 tenth second, and at the 55th second three longs 

 as before are signalled. During the 39th minute 

 two longs, preceding the quarter-second tap at 

 every tenth second, are transmitted, and this- 

 minute concludes as before with the three longs at 

 seconds intervals. 



Bv following the spiral outwards and noting the 

 positions of the longs and shorts in relation to 



