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John Harrison's Birthday



 
 
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Old April 3rd 18, 09:16 AM posted to sci.astro.amateur
Gerald Kelleher
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Default John Harrison's Birthday

The British had such an amazing engineering tradition and perhaps second to none including the technological era of the internet, computers and rocketry. The achievement of John Harrison was among the greatest of them all as a watch in their era to that accuracy was the equivalent of the Apollo mission in terms of innovations and perhaps divides eras as much of the modern era for day to day business relies on accurate clocks.

Astrophysics is an entirely different matter as those men tried to overlay the RA/Dec system on the 24 hour and Lat/Long system by using an observation to check the accuracy of a watch (circumpolar motion) and falsely assign a rotational dynamic to it. I cannot prevent the usual nuisances from hopping in at this stage but were decent and intelligent people think things through, they would discover why the conclusion was terrible -

https://hypertextbook.com/facts/1999/JennyChen.shtml


Any who visits the London museums can see how timekeeping, transport and the telegraph developed in tandem as they refer to transportation and the way people live their lives by the daily cycle. It is a close proximity where astronomy of the great daily and orbital cycles were left behind.

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal
parts (by imaginary lines drawn from North to South) which are called
Degrees of Longitude; and its daily revolution Eastward round its own
axis is performed in 24 hours; consequently in that period, each of
those imaginary lines or degrees, becomes successively opposite to the
Sun (which makes the noon or precise middle of the day at each of
those degrees and it must follow, that from the time any one of
those lines passes the Sun, till the next passes, must be just four
minutes, for 24 hours being divided by 360 will give that quantity; so
that for every degree of Longitude we sail Westward, it will be noon
with us four minutes the later, and for every degree Eastward four
minutes the sooner, and so on in proportion for any greater or less
quantity. Now, the exact time of the day at the place where we are,
can be ascertained by well known and easy observations of the Sun if
visible for a few minutes at any time from his being ten degrees high
until within an hour of noon, or from an hour after noon until he is
only 10 degrees high in the afternoon; if therefore, at any time when
such observation is made, a Timekeeper tells us at the same moment
what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

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