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
Today's mapping tools, satellite imagery, GPS, and geographic information systems technologies make it easy to overlook the fact that determining one's exact location
on the planet was until just a few years ago a long and arduous process.
Part of the challenge has always been because latitude and longitude are more than numbers.
They are angles, measured in degrees, and they are measured off an object much larger than ourselves, the Earth.
Compounding the problem is that the Earth rapidly rotates on its axis at the rate of 15 degrees per hour.
Furthermore, planet Earth is not a perfect sphere, but rather an oblate spheroid.
Wi wider around the equator than it is around the poles.
In addition, the Earth contains numerous anomalies, wrinkles and bulges on and under the surface.
Even the Earth's magnetic poles do not sit exactly underneath the north and south poles.
They are continually moving.
For these and other reasons, determining the latitude and longitude of an object, phenomenon, or event to sub centimeter accuracy.
Did not happen overnight.
Rather, it became possible through a series of inventions, each of which was a revolution in geography.
Backstaff may have originated with Thomas Harriet, English mathematician during the late fifteen hundreds, developed further by Captain John Davis in fifteen ninety four.
The user turned their back on the sun.
Holding the instrument in front with the sun at one's back, one held the instrument so that the shadow cast by this instrument's shadow vein fell on the horizon vein at the side of a slit in the instrument.
One then then moved the sight vein to observe the horizon in a line while maintaining the position of the shadow, permitting reading the angle between the horizon and the sun and
as the sum of the angle from the two arcs.
From thirteen fifty to sixteen hundred the cross staff was also used.
The cross staff was a piece of wood.
Showing 321–340 of 638 · page 17 of 32
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