That
was hint enough. He drew figures upon glass, with varnish,
applied the corroding fluid, then cut away the glass around
the drawing. When the varnish was removed, the figures
appeared raised upon a dark ground.

The swaying to and fro of a chandelier in the cathedral at
Pisa suggested to Galileo the application of the pendulum.

The art of lithography was perfected through suggestions
made by accident. A poor musician was curious to know
whether music could not be etched upon stone as well as
copper.

After he had prepared his slab, his mother asked him to make
a memorandum of such clothes as she proposed to send away to
be washed. Not having pen, ink, and paper convenient, he
wrote the list on the stone with the etching preparation,
intending to make a copy of it at leisure.

A few days later, when about to clean the stone, he wondered
what effect nitric acid would have upon it. He applied the
acid, and in a few minutes saw the writing standing out in
relief. The next step necessary was simply to ink the stone
and take off an impression.

The composition of which printing-rollers are made was
discovered by a country printer in England. It was the
established custom to ink the type on a printing-press with
a pelt-ball--an ink-soaked roll of sheepskin. Having mislaid
his pelt-ball, the ingenious Englishman inked the type with
a piece of soft glue which had fallen out of the glue-pot.
It was such an excellent substitute that, after mixing
molasses with the glue to give the mass proper consistency,
the old pelt-ball was entirely discarded.

The shop of a London tobacconist, by the name of Lundyfoot,
was destroyed by fire. While he was gazing dolefully into
the smoldering ruins, he noticed that his poorer neighbors
were gathering the snuff from the canisters. He tested the
snuff for himself, and discovered that the fire had largely
improved its pungency and aroma.

It was a hint worth profiting by. He secured another shop,
built a lot of ovens, subjecting the snuff to a heating
process, gave the brand a peculiar name, and in a few years
became rich.

The Origin of Tinted Paper.

The origin of blue tinted paper came about by a mere slip of
the hand.

The wife of William East, an English paper-maker,
accidentally let a blue-bag fa