337 
of Edinburgh, Session 1864 - 65 . 
the result of his labours in 1863, with some corrections and addi- 
tions in 1864. It starts fundamentally as a base with my trian- 
gulation of the Flegere and Breven stations, and thus connects 
itself immediately and accurately with the whole of my map so 
far as it extended, that is, from the top of Mont Blanc to the 
“ Nameless Peak A,” parallel to the chain, and from the Jorasses 
to the Flegere in a perpendicular direction. Mr Eeilly carried 
forward the main triangulation up the valley of the Arve to the 
Col de Balme, and thence to the very recesses of the Griacier du 
Tour, which was the seat of at least one part of the “ Grordian 
knot” already referred to. He gradually found himself led to the 
conclusion that the Sardinian surveyors, on whose authority the 
Swiss map beyond the limits of the Confederation was probably 
constructed, had made a mistake of an almost incredible kind, 
representing one and the same mountain under the names of Aiguille 
d'’ Argentiere and Pointe des Plines in two different places a mile and 
a-half apart, and separated by a vast ice-field communicating with 
the Glacier du Tour, which ice-field has of course no existence, as 
the two mountains, by which it was represented as being bounded, 
are, as already stated, absolutely identical. The portion of glacier 
thus annihilated was represented as two and a quarter English 
miles in length. Mr Eeilly, whose activity as a pedestrian is equal 
to his skill as a draughtsman, put the seal on his topographical dis- 
covery by passing for the first time the elevated col between the 
Aiguilles of Argentiere and Chardonnet, starting from the side of 
the glacier of Argentiere. Had existing maps been correct, he 
would have alighted on the glacier of Tour within the frontier of 
Savoy ; but in effect he found himself on the glacier of Salena in 
Swiss territory. 
The western portion of the chain of Mont Blanc next engaged 
his attention. He was enabled by his extraordinary activity, and 
his skill in mountain drawing, to lay down with an accuracy far 
beyond any thing previously attained in that quarter, the whole 
western and southern faces of the chain, with the numerous vast 
glaciers which intersect these. On the whole, the position of about 
200 points was fixed by the theodolite, the position of one or two 
fundamental stations (especially of Mont Joli) having been ob- 
tained from the French engineers. 
2 Y 
VOL. V. 
