Classification and uses of finger prints / by Sir E.R. Henry.

  • Edward Henry
Date:
1913
Catalogue details

Licence: In copyright

Credit: Classification and uses of finger prints / by Sir E.R. Henry. Source: Wellcome Collection.

    120/168 (page 108)
    Finger perspiration marks on blades of knives or on plated goods are photographed in a similar manner, but the velvet-lined box is not needed. The lighting is sometimes difficult since the article must be placed and lighted in such a way that the impression will appear on the screen light on a dark ground. A little patience is rewarded by obtaining the desired result. Similar imprints on glass bottles and tumblers are photographed by the preceding method, but the bottles are filled with a black or dark red fluid to get the necessary contrast. Tumblers can be filled with a similar liquid when the marks are on the outside of the glass, but, as a rule, better results are obtained by placing a piece of dead black paper in contact with the whole of the inside surface of the vessel with the exception of that part covered by the finger print. Another sheet of this paper prevents light entering the top. The convexity of bottles, etc., is sometimes the cause of reflections appearing over a part of the area covered by the finger impression. This is removed by altering the position of the lamps. AAffien finger prints are found on the smooth side of corrugated glass, the numerous reflections are removed by filling the uneven surface with black printing ink. The ridges of fingers when impressed heavily on a candle create furrows similar in pattern to those of the ridges. Before being photographed such imprints are treated in the following manner :—The impres- sion is covered with printing ink, superfluous ink being