This process creates lenses that are exceptionally clear and free of distortions.
Owing to the great extent of Asia, it is not easy to obtain a correct conception of the actual form of its outline from ordinary maps, the distortions which accompany projections of great and misleading.
The plates in this last are by Barraband, for many years regarded as the perfection of ornithological artists, and indeed the figures, when they happen to have been drawn from the life, are not bad; but his skill was quite unable to vivify the preserved specimens contained in museums, and when he had only these as subjects he simply copied the distortions of the " bird-stuffier."
Hence some stalactites have their tips under water long enough to allow tassels of crystals to grow on them, which, in a drier season, are again coated over with stalactitic matter; and thus singular distortions are occasioned.
Adams make its direction downwards; but round the rim and on bridges the characteristic distortions due to eruptive prominences are often observed.