Joseph Kerski
speaker
638 appearances
3 recordings
1 series
first heard Jun 2026
last heard 1 Aug
Joseph Kerski’s voice in public audio — every appearance, attributed to the second.
Trend
recordings per month · last 12 monthsRecordings per month over the last 12 months — 3 in all, peaking in Aug 2026 with 1.
Appearances
One piece was the staff, and attached at its middle was a perpendicular cross piece, able to slide up and down along it in the manner of a mid twentieth century slide rule.
A cross staff could measure the angle between the directions of two stars or measure the angle of the noontime sun.
Above the horizon, which allowed people to estimate their latitude.
From four hundred to sixteen hundred, the astrolabe was heavily used to determine the time of sunrise or sunset at one's location.
or the positions of the stars and planets.
The planispheric astrolabe had the celestial sphere projected onto the plane of the equator.
Most were made of brass up to six inches or fifteen centimeters in diameter.
A mariner's astrolabe from the fourteen hundreds through the fifteen hundreds was used to determine one's latitude on the Earth.
One did so by determining the position above the horizon and
of the sun or another star of known declination.
or angle above the horizon using a brass ring in degrees with a rotating allidade for sighting the sun or star.
However, it was seldom that simple due to waves on ships making it difficult to measure, cloud cover, and difficulty in reading the instrument itself.
Another major development, the sextant S E X T A N T uses adjustable mirrors to measure the exact angle of the sun, stars, moon,
Above the horizon.
Its name derived from a Latin word for one-sixth because the curved frame of the sextant represented one-sixth of a circle.
From the measured angles and an almanac indicating the positions of these objects at different times of the year and for different latitudes, ship captains could determine their latitude in clear weather day or night.
Around seventeen thirty Hadley and Godfrey laid out the principles of the Sexton.
Though later the principles were also found in earlier unpublished writings of Isaac Newton, sixteen forty-three to seventeen twenty-seven.
Scholars
have pointed out that navigational instruments were simultaneously advancing rapidly in China as well.
Showing 341–360 of 638 · page 18 of 32
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