

WIRELESS TIME SIGNALS. 269 



Explanation of Plate XX. 



(A.) — Reproduction (reduced one-fifth) of Foucault-penduluin 

 photograph (geogyrogram) taken 1916, March 4, from 2 h. 37 m. 

 54 s. a.m. to 4 h. 37 m. 55 s. a.m., (Sydney standard time). The 

 exposures (in pairs) were made every five minutes, and the change 

 of azimuth in the intervals is clearly seen. The twentieth pair of 

 exposures was missed, owing to an accidental interruption. 



Sh. indicates the edge of the occulting shutter or screen during 

 the five-minute intervals. 



C. is the zero-point of the oscillations. 



(B.) — Cardan Suspension (see text-figure 4). 



(N.B. — Text figures not strictly to scale.) 



WIRELESS TIME SIGNALS— SOME SUGGESTED 



IMPROVEMENTS. 



By W. E. and P. B. Cooke. 



{Read before the Royal Society of N. S. Wales, December 6, 1916 J] 



Anticipating a re-determination of Australian longitudes 

 by means of trans- Pacific radio signals, some experimental 

 work has been recently undertaken at the Sydney Obser- 

 vatory, with a view of eliminating certain sources of error. 



Prior to the war great and rapid progress was made with 

 the new methods, culminating in the determination of the 

 difference of longitude between Paris and Washington by 

 means of radio signals across the Atlantic. In the course 

 of this work every possible precaution to ensure great 

 accuracy was taken. The results were undoubtedly good, 

 but one gathers from the remarks of M. Baillaud (Director 

 of the Paris Observatory) and others that there are still 



