64 Transactions. 



records on a tape. It is provided with two styles, side by side. 

 The one records, embossing by make-circuit, the second-beats of 

 the sidereal clock, while the other similarly records the signals 

 by the transit -key, also the clock or arbitrary signals received 

 (from Doubtless Bay) when making a comparison of the clocks 

 lor the determination of the difference of longitude. The transit 

 and arbitrary signals on the tape are readily interpolated and 

 expressed in time from the embossed dots or records indicating 

 the seconds of the local sidereal clock. 



Electric Apparatus. — Mr. J. K. Logan, Superintecdent of 

 Government Telegraphs, has furnished the following description 

 and diagram of the arrangement especially installed at the Wel- 

 lington Observatory for the differential longitude work with 

 Doubtless Bay, as this was the first time that an automatic 

 exchange of clock-signals had been made with the observatory. 

 (The Wellington clock made contact (circuit) every second, while 

 the chronometer at Doubtless Bay was arranged to " break " 

 circuit.) 



Two British Post Office polarised relays, the coils of each of 

 which were joined in parallel, giving a resistance of 150 ohms 

 for each relay, were connected in multiple through three Le- 

 clanche cells to the terminals of the clock. 120 Leclanche cells, 

 with the copper earthed, were joined to one of the local termi- 

 nals of one of these relays, and, by adjustment, the tongue of 

 this relay was made to bear against the stop connected to that 

 terminal. The terminal connected with the tongue was then 

 joined to the copper terminal of a Siemens relay of 500 ohms re- 

 sistance. The line was connected to the Z (zinc) terminal of 

 the Siemens relay through a s%vitch arranged to disconnect it 

 from the time-recording instruments and connect it to the speak- 

 ing (Morse) instruments when required. The local terminals of 

 the second British Post Office polar relay were connected through 

 eight Leclanche cells to the terminals of the magnet-coils of the 

 back st3de of the chronograph. The local terminals of the Siemens 

 relay were conducted through eight Leclanche cells to the termi- 

 nals ot the magnet-coils of the front style of the chronograph. 

 At every make of the clock the tongue of the Post Office relay 

 that was connected to the back style of coils made contact and 

 caused the style to emboss, thus registering every clock-beat. 

 The other Post Office relay at every beat of the clock broke con- 

 tact at its tongue : the line-current was thus broken and a signal 

 recorded at Doubtless Bay. As this line-current passed through 

 the Siemens relay at the observatory, and while passing held 

 the tongue of that relay open against the bias given to it, at 

 every break of the current the tongue, by reason of that bias, 

 moved across and closed the local circuit, thereby recording 

 marks on the front style. When signals were to be received 



