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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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