Klotz. — Trunspacific Longikidis. bl 



relay, and. as the clock or chronometer breaks circuit every 

 two seconds (omitting the 58th second so as to identify the 

 minute), the points of the clock relay separate every two seconds, 

 and hence record the clock-beats on the chronograph. In the 

 chronograph-circuit is the break-circuit observing-key too, by 

 means of which the transit of eacli star over the eleven threads 

 is recorded. 



It is customary when beginning the exchange to put the 

 telegraph-line for a minute at each station over the points of 

 the clock relay, whereby the circuit of the main line is broken 

 by each chronometer every two seconds — that is, we let the 

 clocks (chronometers) record simultaneously over the line, each 

 chronograph thus obtaining the record of both clocks. From this 

 record we immediately see the relative position of the respec- 

 tive minutes — in fact, of the seconds too — enabling one readily 

 to identify corresponding arbitrary signals, by means of which 

 the more accurate chronometer-comparison is made. Theoreti- 

 cally, the comparison by the chronometers recording directly 

 over the line, as above, is as good as by arbitrary signals. The 

 trouble lies in scaling or measuring the former. As, for an 

 interval of a minute, the relative position of the two-second 

 breaks of the two chronometers is the same, after having mea- 

 sured one such interval on the chronograph sheet the mind 

 is involuntarily biassed ; we know that all the others should be 

 the same, and. consequently, we cannot measure, say. thirty, 

 our minimum number, with that freedom of mind which would 

 be the case if we did not know what measure to expect : hence 

 the device of the arbitrary signals. In this case each chrono- 

 meter records only on its own chronograph. One observer now 

 sends by means of the signal (break-circuit) key twenty arbitrary 

 signals ; the chronograph - circuit, which always passes over 

 the points of the clock relay, is now made to pass too over the 

 points of the signal relay, which is on the main-line circuit. 

 Hence a signal sent will be recorded on each chronograph, and 

 each chronograph has its own chronometer-record for interpreting 

 any signal, just as it interprets the transits while observing. 



As the word implies, these arbitrary signals are intentionally 

 made irregular, and will average about two seconds apart. The 

 other observer now sends, similarly, forty signals, and again 

 the former twenty more, so that the mean of the times of sending 

 of the two observers about coincides, thereby eliminating differ- 

 ential rate of the two chronometers. It is customary when 

 sending signals to give a rattle with the key at the beginning 

 and end of each set. If there is no trouble on the line the whole 

 exchange is over in five minutes. A few minutes are required 

 for conversation about the condition of the sky. If the prospects 



