196 



SCIENCE 



[N. S. Vol. XXVI. Xo. 659 



Morris has brought to a conclusion the re- 

 ductions of the geodetic survey of the 

 Transvaal and Orange River Colony, and 

 his report is now in my hands for publica- 

 tion. 



Dr. Rubin, under my direction, at the 

 cost of the British South Africa Company, 

 has carried the arc of meridian northwards 

 to south latitude 9° 42', so that we have 

 now continuous triangulation from Cape 

 L'Agulhas to within fifty miles of the 

 southern end of Lake Tanganyika; that is 

 to say, a continuous geodetic survey ex- 

 tending over twenty-five degrees of lati- 

 tude. 



It happens that, for the adjustment of 

 the international boundary between the 

 British Protectorate and the Congo Free 

 State, a topographic survey is at the 

 present moment being executed northward 

 along the thirtieth meridian from the 

 northern border of German East Africa. 

 A proposal on the part of the Royal So- 

 ciety, the Royal Geographical Society, the 

 British Association and the Royal Astron- 

 omical Society has been made to strengthen 

 this work by carrying a geodetic triangula- 

 tion through it along the thirtieth meri- 

 dian, and thus adding 2J° to the African 

 are. These societies together guarantee 

 1,000Z. towards the cost of the work, and 

 ask for a like sum from government to 

 complete the estimated cost. The topo- 

 graphic survey will serve as the necessary 

 reconnaisance. The topographic work will 

 be completed by the end of January next, 

 and the four following months offer the 

 best season of the year for geodetic opera- 

 tions in these regions. 



There is a staff of skilled officers and 

 men on the spot sufficient to complete the 

 work within the period mentioned, and the 

 Intercolonial Council of the Transvaal and 

 Orange River Colony most generously 

 offers to lend the necessary geodetic instru- 



ments. The work wiU have to be done 

 sooner or later, but if another expedition 

 has to be organized for the purpose the 

 work will then cost from twice to three 

 times the present amount. One can not, 

 therefore, doubt that His Majesty's gov- 

 ernment will take advantage of the present 

 offer and opportunity to vote the small 

 sum required. This done, we can not 

 doubt that the German government will 

 complete the chain along the eastern side 

 of Lake Tanganyika, which lies entirely 

 within their territory. Indeed, it is no 

 secret that the Berlin Academy of Sciences 

 has already prepared the necessary esti- 

 mates with a view to recommending action 

 on the part of its government. 



Captain Lyons, who is at the head of the 

 survey of Egypt, assures me that prelimi- 

 nary operations towards carrying the arc 

 southwards from Alexandria have been be- 

 gun, and we have perfect confidence that 

 in his energetic hands the work will be 

 prosecuted with vigor. In any case the 

 completion of the African are will rest 

 largely in his hands. That arc, if ever my 

 dream is realized, will extend from Cape 

 L 'Agulhas to Cairo, thence round the east- 

 ern shore of the Mediterranean and the 

 islands of Greece, and there meet the 

 triangulation of Greece itself, the latter 

 being already connected with Struve's 

 great arc, which terminates at the North 

 Cape in lat. 70° N. This will constitute 

 an arc of 105° in length— the longest are 

 of meridian that is measurable on the 

 earth's surface. 



THE SOLAE PABALLAX 



Much progress has been made in the 

 exact measurement of the great funda- 

 mental unit of astronomy— the solar 

 parallax. 



Early in 1877 I ventured to predict^ 



'"The Determination of the Solar Parallax," 

 The Observatory, Vol. I., p. 280. 



