The Weight of Deep Water on a Man, and Ultra-Sensitive Balances
Why a man cannot stay in the depths, and balances that tip at the least difference of weight
The opening passage reasons about the pressure of deep water: a man set 3 or 4 miles down would be loaded by a column of water as thick as a man and 4 miles high, and would be crushed almost to nothing, so experience shows water thrusts a man back toward the surface. The rest of the folio describes several extremely sensitive balances (b f, s t) that dip below their centre at the least disparity of weight and can never be brought level, with a caution to beware moving air. The diagrams show horizontal balance beams with box weights and pivots, and two bent-arm forms below.
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The crushing weight of a deep column of water on a man
At a depth of 3 or 4 miles a man would be loaded by a column of water as thick as a man lying down and 4 miles high; it would be impossible for him not to be turned into water, that is into nothing, under so great a weight. Experience shows a man cannot stay in great depth without the water thrusting him by force toward the surface.
A balance sensitive to imperceptible differences
This balance goes below its centre at the least disparity of weight and serves to weigh the smallest thing, but one must beware the movement of the air. If the balance b f is well made it will show almost the differences of imperceptible things, its supports a n set beneath so it does not tip below its centre f.
Pivot in the middle of the beam tips along its length
If the pivot is set in the middle of the thickness of the balance, the balance will tip along the line of its length whenever its weights are unequal. This balance moves through different descents for different inequalities and can never be righted to a perpendicular line.