It was my good fortune to be in some degree connected with the investigations respecting the limitation of Periods, for which the geology of Switzerland afforded peculiar facilities. My early home was near the foot of the Jura, where I constantly faced its rounded domes, and the slope by which they gently descend to the plain of Switzerland. I have heard it said that there is something monotonous in the continuous undulations of this range, so different from the opposite one of the Alps. But I think it is only by contrast that it seems wanting in vigor and picturesqueness; and those who live in its neighborhood become very much attached to the more peaceful character of its scenery. Perhaps my readers will pardon the digression, if I interrupt our geological discussion for a moment, to offer them a word of advice, though it be uncalled for. I have often been asked by friends who were intending to go to Europe what is the most favorable time in the day and the best road to enter Switzerland in order to have at once the finest impression of the mountains. My answer is always,--Enter it in the afternoon over the Jura. If you are fortunate, and have one of the bright, soft afternoons that sometimes show the Alps in their full beauty, as you descend the slope of the Jura, from which you command the whole panorama of the opposite range, you may see, as the day dies, the last shadow pass with strange rapidity from peak to peak of the Alpine summits. The passage is so rapid, so sudden, as the shadow vanishes from one height and appears on the next, that it seems like the step of some living spirit of the mountains. Then, as the sun sinks, it sheds a brilliant glow across them, and upon that follows--strangest effect of all--a sudden pallor, an ashy paleness on the mountains, that has a ghastly, chilly look. But this is not their last aspect: after the sun has vanished out of sight, in place of the glory of his departure, and of the corpse-like pallor which succeeded it, there spreads over the mountains a faint blush that dies gradually into the night. These changes--the glory, the death, the soft succeeding life--really seem like something that has a spiritual existence. While, however, I counsel my friends to see the Alps for the first time in the afternoon, if possible, I do not promise them that the hour will bring with it such a scene as I have tried to describe. Perfect sunsets are rare in any land; but, nevertheless, I would advise travellers to choose the latter half of the day and a road over the Jura for their entrance into Switzerland.[3]