b b - d a (?). The right angle should be whole.

a b should be of the length of b c, so that when the end a descends to b, c has made its final movement, because b c is as much as c d. The motion of the pen begins at a g h. Let the point c be made at an angle, and let a contrary angle be at a. b b, from the ring upward, should be square with its slot; and inside that ring, down to the foot from where it enters the ring of the set-square, let it be round.

Of the consumption, or evaporation, of the water of the Mediterranean Sea. The Mediterranean Sea, a very great river set between Africa, Asia and Europe, gathers into itself about three hundred royal rivers and, besides these, receives the rains that fall upon it over a space of three thousand miles. It returns to the great Ocean sea its own and the other received waters, and without doubt gives less to the [Ocean] sea than it receives, because many veins descend from it which run through the bowels of the earth to vivify that terrestrial machine. And this is necessary because the surface of that Mediterranean is more remote from the centre of the world than the surface of that Ocean, as is proved in the second [book] of this. And besides this, the heat of the sun continually evaporates much of that Mediterranean water; and for this reason that sea can gain little increase from the said rains, or suffer little diminution from pouring the received waters into the Ocean, or from being evaporated by the heat of the sun or by the course of the dry winds.