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OCR Rendition - approximate
8 4 FINGER PRINTS CHAP. unit of the scale would be one-fortieth of an inch ; if six ridges one-sixtieth, and so forth. There is no theoretical or practical difficulty, only rough indications being required. It is unnecessary to describe in detail how the bearings of any point may be expressed after the fashion of compass bearings, the direction I-0 taking the place of East-West, the uppermost direction that of North, and the lowermost of South. Little more is practically wanted than to be able to describe roughly the position of some remarkable feature in the print, as of an island or an enclosure. A ridge that is characterised by these or any other marked peculiarity is easily identified by the above means, and it thereupon serves as an exact basis for the description of other features. Purleenje's " Commentatio." Reference has already been : made to Purkenj e, who has the honour of being the person who first described the inner scrolls (as distinguished from the outlines of the patterns) formed by the ridges. He did so in a University Thesis delivered at Breslau in 1823, entitled Commentatio de examine physiologico organi visas et systematis cutanei (a physiological examination of the visual organ and of the cutaneous system). The thesis is an ill-printed small 8vo pamphlet of fifty-eight pages, written in a form of Latin that is difficult to translate accurately into free English. It is, however, of great historical interest and reputation, having been referred to by nearly all
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