I had thought of this subject since I first read the conjectures of De Saussure on the temperature of Mont Blanc; but in 1857 I met Auguste Balmat at the Jardin, and there learned from him that he entertained the idea of placing a self-registering thermometer at the summit of the mountain. Balmat was personally a stranger to me at the time, but Professor Forbes's writings had inspired me with a respect for him, which this unprompted idea of his augmented. He had procured a thermometer, the graduation of which, however, he feared was not low enough. As an encouragement to Balmat, and with the view of making his laudable intentions known, I communicated them to the Royal Society, and obtained from the Council a small grant of money to purchase thermometers and to assist in the expenses of an ascent. I had now the thermometers in my possession; and having completed my work at Zermatt and Saas, my next desire was to reach Chamouni and place the instruments on the top of Mont Blanc. I accordingly descended the valley of the Rhone to Martigny, crossed the Tete Noire, and arrived at Chamouni on the 29th of August, 1858. [Sidenote: DIFFICULTIES AT CHAMOUNI. 1858.] Balmat was engaged at this time as the guide of Mr. Alfred Wills, who, however, kindly offered to place him at my disposal; and also expressed a desire to accompany me himself and assist me in my observations. I gladly accepted a proposal which gave me for companion so determined a climber and so estimable a man. But Chamouni was rife with difficulties. In 1857 the Guide Chef had the good sense to give me considerable liberty of action. Now his mood was entirely changed: he had been "molested" for giving me so much freedom. I wished to have a boy to carry a small instrument for me up the Mer de Glace--he would not allow it; I must take a guide. If I ascended Mont Blanc he declared that I must take four guides; that, in short, I must in all respects conform to the rules made for ordinary tourists. I endeavoured to explain to him the advantages which Chamouni had derived from the labours of men of science; it was such men who had discovered it when it was unknown, and it was by their writings that the attention of the general public had been called towards it. It was a bad recompense, I urged, to treat a man of science as he was treating me. This was urged in vain; he shrugged his shoulders, was very sorry, but the thing could not be changed. I then requested to know his superior, that I might apply to him; he informed me that there were a President and Commission of guides at Chamouni, who were the proper persons to decide the question, and he proposed to call them together on the 31st of August, at seven P.M., on condition that I was to be present to state my own case. To this I agreed.