Measuring a ship's speed with a mercury clock and a right angle

A quicksilver timer for one hour

Quicksilver is to measure one hour, the hour divided into degrees, minutes and seconds, the mercury made to drip; a rule of the run is then set on the standard. The graduated hourglass-like vessels drawn on the sheet carry the falling mercury.

Keep a little mercury in the ball to the spout

In the ball there should always remain a little quicksilver, up to the mouth of the little spout that pours it out, so the flow stays even.

Ship travels as far as the powder falls in one time

Given the beat of time at a and uncorked, one notes how long the poured matter takes to strike at n. Lowering the wheel n by a screw sets the descent to one harmonic time; when the motions are equal the ship travels exactly as far as the powder descends, so everything can be measured.

The right angle K a h with equal sides

A small right angle K a h is laid out; when in the course the two sides of that right angle made by the pouring K h come out equal, the motions are declared equal. The right-angle triangles drawn on the sheet embody this test.

Horizontal motion a b exceeds the central descent a c

The horizontal motion is greater than the central (downward) motion by as much as the line a b is longer than a c, because a b is the true motion of the ship and a c the true descent of the weight, and neither deceives the experiment since they are not impeded by wind or by motion.

Reliable only with steady wind

The instrument serves only with the wind, because then the boat goes with fewer jolts, keeping its motion even enough to be measured.

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Nella metà superiore del foglio gruppo di figure con scritte.

Nella metà inferiore del foglio a destra figura con:

Sotto la figura:

A sinistra figura con lettere e scritte.

A lato e sotto la figura:

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Gruppo di figure con lettere e scritte.

In the upper half of the sheet, a group of figures with writing.

In the lower half of the sheet, at the right, a figure with:

Below the figure:

At the left, a figure with letters and writing.

Beside and below the figure:

Group of figures with letters and writing.