336 Froceedincjs of the Royal Society 
chain of Mont Blanc. But as opportunity served, I have not ceased 
to urge the younger generation of Alpine travellers-to extend our 
knowledge of its details, and, by making the theodolite their com- 
panion, and multiplying panoramic views of all intricate mountain 
groups, to obtain valuable topographical knowledge, at the same 
time that they enjoy the luxury of Alpine rambling. The south- 
western part of the chain of Mont Blanc, which really was very much 
a terra incognita as to its interior conformation (though perpetually 
visited on its outskirts by all who passed the Col du Bonhomme), 
was partially explored and sketched by Mr Tuckett, an active 
member of the Alpine Club ; but the district to the east of the Mer 
de Grlace, stretching towards the Col de Balme and the Swiss Vai 
Ferret, remained a complete enigma, the intricacy and obscurity 
of which appeared more and more as its recesses were successively 
invaded by the adventurous inroads of members of the Alpine Club. 
For years I had been urging my mountaineering friends to carry a 
theodolite to the summit to the east of the Jardin, marked in my 
map as ‘‘ Nameless Peak A,” from whence I knew that the de- 
batable land to the eastward would probably be overlooked ; but 
it was not attempted till 1863. The year before. Sheet xxii. of 
the Swiss Federal Survey had been issued, and was looked for with 
great interest by myself and others as likely to clear up at least a 
part of the mystery of this Grordian knot of peaks and glaciers. So 
far as it was included within the rigorous limits of the Swiss Con- 
federation, it was as completely satisfactory as that survey has 
everywhere else been acknowledged to be. But the Federal boun- 
dary once passed, it was evident that the topography of the ad- 
jacent part of Savoy included in the Swiss sheet was far less reliable, 
if indeed worthy of any confidence at all. The persuasion of the 
uncertain state of the geography of this interesting portion of the 
most important mountain group in Europe was common to myself 
and others who had visited or crossed that part of the chain. 
Early in 1863 I had the good fortune to make the acquaintance 
of Mr Eeilly, who was already interested in the problem, and who 
shewed me panoramic drawings of different parts of the range, 
executed with remarkable facility and correctness. He readily 
agreed to return to the spot and take a theodolite with him. The 
map which I now have his permission to exhibit to the Society is 
