strong light.

Which of two inklines crossing each other was made first, is not
always easy of demonstration. To the inexperienced observer the
blackest line will always appear to be on top, and unless the examiner
has given much intelligent observation to the phenomenon and the
proper methods of observing it mistakes are very liable to be made.
Owing to the well-known fact that an inked surface presents a stronger
chemical affinity for ink than does a paper surface, when one ink-line
crosses another, the ink will flow out from the crossing line upon the
surface of the line crossed, slightly beyond where it flows upon the
paper surface on each side, thus causing the crossing line to appear
broadened upon the line crossed. Also an excess of ink will remain in
the pen furrows of the crossing line, intensifying them and causing
them to appear stronger and blacker than the furrows of the line
crossed.

It is probable that ink and pencil alterations and erasures are more
frequently made with a sharp steel scraper and ink-erasing sand rubber
than otherwise. By these methods the evidence--first, the removal of
the luster or mill-finish from the surface of the paper; second, the
disturbance of the fibre of the paper, manifest under a microscope;
third, if written over, the ink will run or spread more or less in the
paper, presenting a heavier appearance, and the edges of the lines will
be less sharply defined; fourth, if erasure is made on ruled paper, the
base line will be broken or destroyed over the scraped or rubbed
surface; fifth, the paper, since it has been more or less reduced in
thickness where the erasure has been made, when held to the light will
show more or less transparency. When erasures have been thus made the
surface of the paper may be resized and polished, by applying white