igoS] OF THE ALASKA BOUNDARY. 89 



agreement was reached and embodied in the treaty signed at Wash- 

 ington in August, 1906. This treaty provided for the survey and 

 demarcation of the line and before the end of that summer the tele- 

 graphic determination of the Yukon River crossing of the 141st 

 meridian had been completed. The telegraphic determination made 

 by the Americans rests on the knc^v^n longitude of Seattle. Signals 

 were exchanged between Sitka and Seattle, Seattle and Valdez, 

 Valdez and Fort Egbert, Fort Egbert and the boundary. That made 

 ' by the Canadians rests on the longitude of Vancouver between which 

 place and the boundary time signals were exchanged. As the differ- 

 ence between Seattle and Vancouver was also determined by the 

 commissioners, the circuit was closed and a very satisfactory agree- 

 ment was obtained. 



It is worthy of remark in passing that the tracing of a meridian 

 or parallel on the ground involves considerations which do not 

 become apparent by an inspection of an artificial globe on which 

 these lines are traced as smooth and regular curves. A parallel of 

 latitude must be determined by astronomical observations, but in 

 general the circumference of a small circle of the earth parallel to 

 the equator will not lie in the same astronomical latitude, owing to 

 the so-called deflection of the vertical. A series of points deter- 

 mined astronomically as being in the same latitude or, as in the case 

 of a meridian, in the same longitude, will therefore in general pro- 

 duce on the surface of the earth a zig-zag line when they have been 

 joined together. 



In order to avoid all questions that might arise from local deflec- 

 tions of the zenith, it was provided by the Treaty of 1906 that the 

 commissioners should determine by the telegraphic method a con- 

 venient point on the 141st meridian and then trace a north and south 

 line passing through the point thus ascertained. This provision 

 fixed the telegraph crossing of the boundary as the initial point for 

 the longitude determination. The commissioners desired to make 

 the determination as nearly on the 141st meridian as possible, in 

 order to avoid a deflection error which might have been involved if 

 the longitude had been obtained by linear measurement from a lon- 

 gitude observed at some distance from the boundary. The transit 

 pier erected for the purpose of exchanging time signals was found 



