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Rh my fellow-travellers, who was a builder, or else a master mason, told me that the way in which red sandstone buildings last depends entirely on the way in which the stone is laid. It must lie as it dots in the quarry; but he said that very few workmen could always tell the difference between the joints of planes of cleavage and the—something else which I couldn't catch,—by which he meant, I suppose, planes of stratification. He said too that some people, though they were very particular about having the stone laid well, allowed blocks to stand in the rain the wrong way up, and that they never recovered one wetting. The stone of the same quarry varies much, and he said that moss will grow immediately on good stone, but not on bad. How curious,—nature helping the best workman!" Thus far my favourite pupil!

151. 'Moss will grow on the best stone,' The first thing your modern restorer would do is to scrape it off; and with it, whatever knitted surface, half moss root, protects the interior stone. Have you ever considered the infinite functions of protection to mountain form exercised by the mosses and lichens? It will