The results in each of the two methods were sometimes quite right,
sometimes quite wrong, sometimes neither one nor the other. The latter
depended on the individual judgment as to which class it belonged, and
might be battled over with more or less show of reason by advocates on
opposite sides. Equally dividing these intermediate cases between "right"
and "wrong," the results were obtained as shown. In one, and only one, of
the cases, the most reasonable interpretation had not been given, and the
result had been wrong when it ought to have been right. The purely
personal error was therefore disregarded, and the result entered as
"right."
III. A third attempt was made by a different method, upon the lineations
of a finger print drawn on about a twenty-fold scale. It had first been
enlarged four times by photography, and from this enlargement the axes of
the ridges had been drawn with a five-fold enlarging pantagraph. The aim
now was to reconstruct the entire finger print by two successive and
independent acts of interpolation. A sheet of transparent tracing-paper
was ruled into six-ridge-interval squares, and every one of its alternate
squares was rendered opaque by pasting white paper upon it, giving it the
appearance of a chess-board. When this chequer-work was laid on the print,
exactly one half of the six-ridge squares were masked by the opaque
squares, while the ridges running up to them could be seen. They were not
quite so visible as if each opaque square had been wholly detached from
its neighbours, instead of touching them at the extreme corners, still the
loss of information thereby occasioned was small, and not worth laying
stress upon. It is easily understood that when the chequer-work was moved
parallel to itself, through the space of one square, whether upwards or
downwards, or to the right or left, the parts that were previously masked
became visible, and those that were visible became masked. The object was
to interpolate the ridges in every opaque square under one of these
conditions, then to do the same for the remaining squares under the other
condition, and finally, by combining the results, to obtain a complete
scheme of the ridges wholly by interpolation. This was easily done by
using two sheets of tracing-paper, laid in succession over the
chequer-work, whose position on the print had been changed meanwhile, and
afterwards tracing the lineations that were drawn on one of the two sheets
upon the vacant squares of the other. The results are given in the third
column of the table.
Public-domain text, read in full here on John Shaqi.
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