On a Series of Lantern Slides. By Dr. A. Clifford Mercer. 307 
" exclamation marks ” are broken off in exact line with the general 
line of fracture, as though they were throughout their length part of 
the substance of the scale. Slide 47 (plate IY. fig. 6) is an 
enlargement from a negative showing a rent in a Fodura scale 
passing in from one edge nearly transversely across some exclamation 
marks. In several instances the broad part of the mark is undisturbed 
on one edge of the rent, and the corresponding point undisturbed on 
the other. In slide 48 the exclamation marks are in one part seen 
bent, with a bend in the general substance of the scale. In another 
part is an appearance suggesting that a transverse section of a scale 
would have a corrugated outline. In slide 49 (plate IY. fig. 7) 
another bent Fodura scale gives a still more marked hint of corruga- 
tion, and leads us to suppose that the convexities of corrugation at 
one surface would correspond with the exclamation marks. Will 
not some delicate worker stain Podura scales, cut sections of them by 
some imbedding process, and establish or overthrow this hypothesis ? 
Photomicrographs of Printed and Written Matters. 
The irregular distribution of printer’s ink on the fibrous surface of 
an ordinary newspaper is seen in slide 20. The microscopic character 
of the engraver’s hatch and stipple in a United States two cent postage 
stamp is seen in slide 22. 
Slide 23 (fig. 34) is a photomicrograph of a quickly-made pen- 
and-ink crossing, showing the free flowing of the ink of one line into 
that of the other, a mingling of the inks. All trace of borders to 
either line is lost at the crossing. The ink of the first line must have 
been quite wet when the crossing stroke was made. Had the first 
line been partially or quite dry, the ink of the second line would have 
overflowed to the first but partially or not at all. Of the truth of 
these statements I have satisfied myself by the examination of several 
thousand pen-and-ink crossings, made under greatly varying conditions 
as to pen, ink, paper, and interval of time between the two strokes. 
If the first ink be perfectly dry, the second ink is not more likely to 
overflow its borders at the crossing than elsewhere on the surface of 
the paper. Slide 24 (plate IV. fig. 8) shows the greater portion of a 
letter J from a forged document. This document was first written in 
pencil and then gone over with a bolder hand in ink, as was demon- 
strated by the Microscope finding bits of graphite here and there 
where the ink had failed to wholly cover the pencil lines. The forger 
then shaded certain letters he had missed shading, one of which was this 
J in his father’s signature. As the J was dry when the shading was 
added, the ink of the shading stroke did not overflow to the under- 
lying line. The shading stroke is as distinct as if it had been made 
on a fresh surface of the paper. A special reason for the forger not 
originally shading the J was that he habitually penned a j in a 
direction reverse to that habitual with his father. 
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