The Eye and Light; and Fire Struck from Iron
A distant light seen through a small hole, and sparks kindled by hammering iron
A small diagram at upper right shows lines from the sun and its reflection in water to an observing eye, labelled sun, water, reflected sun. One note, 'Of the eye and light,' observes that a luminous body seen at a distance through a tiny hole appears to shrink, while one seen from close by makes no change. A second note, 'Of the blow, cause of fire,' reports that striking a thick iron wire repeatedly on one same spot between anvil and hammer will kindle tinder there. Much of the surrounding text is faint with the verso showing through.
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Sun and its reflection seen by the eye
The upper-right sketch traces rays from the sun and from its reflection in water to an eye, with the labels sun, water, and reflected sun.
A distant light seen through a small hole
Under the heading 'Of the eye and light,' a luminous body of long distance viewed through a small hole seems to diminish, whereas seen close it makes no change; at one or two braccia from the hole there is no difference whether seen through the hole or beside it.
Fire kindled by hammering iron
Under 'Of the blow, cause of fire,' striking a thick iron wire with frequent blows on one same spot, between anvil and hammer, will kindle the tinder at the beaten spot.