could this be a mathematical way to obtain longitude without clock? Please help

mfb

There is no expected error in the traditional method with a clock. Your method does not represent the traditional method, and would lead to a large error not present there.

sophiecentaur

It's longitude that's the problem. If you can see the Sun at midday and you have a working calendar then you know your latitude.
With a set of ephemeris tables, a telescope and a sextant and a bit of time, you could decide where you were even if you had been asleep for an unspecified time. The time would be needed to get yourself into the right month of the right year.
Of course it's not necessary today but, when the bomb drops and you need to find that tiny island in the middle of the ocean, the clock-less and GPS-less solution is always there - and it's surprisingly accurate. And, hey, it's not the most random and pointless procedure that I've read on these fora!

antonio glez

yes theres an expected error in the traditional method and its the error of the clock

if the clock has an error of 24 hours along 10 day youll make an error in your position of exactly 360º

now with my system of virtual stars rotating opposite sense in the sky from a 24 hour error in the clock along 10 days you misspoint longitude in 36º

unless im wrong of course thats why i post

sophiecentaur

The system still relies on an accurate time measurement - however you dress it up. You still need to know where these "Virtual stars" are supposed to be at the time you do your observation.

mfb

:(
Used the wrong word one time and you found it. Actually, the statement is even more accurate that way .


@antonio glez: What you call "expected error" is the actual method to determine longitude.

sophiecentaur

I thought it was a slip!

antonio glez

well by error i meant a clock measures 25 hour where an atomic clock measures 24

the longitude is obtained traditionally by comparing LOCAL time from GREENWHICH time

the way i see the polinesian kept track of the virtual stars, the needles, by the angle sun-moon which is an UNIVERSAL 28 day clock and then augment precision with this system i try to explain

i insist using the moon-sun as a 28 day clock(with which you have greenwhich time to compare to your local time) was the solution to the longitude problem most extended untill radios to syncronize clocks appeared

oh i forgot:

local time: position of the sun at where you are, sun in the top noon, 1200

greenwhich time : position of the sun in greenwhich

sophiecentaur

When we look at evidence of what ancient people achieved we really need to get things in context. We cannot do experiments on them - we can only see the surviving evidence of their successes. What routes did they actual travel reliably? If they stuck to voyages with constant latitude then they would not have needed to do the longitude thing at all. If they put in an easy North South dog-leg, by island hopping etc., they could then have taken an East West route over the horizon and been able to retrace their path to get home, reliably. We know about smart navigation by birds and fish. It's quite possible that humans could have followed the directions of flocks of seabirds to reach destinations way over the local horizon. Ocean swell can be stable in height, wavelength and direction for days and days at a time, giving direction and even an idea of distance (counting waves).

Is there any point in writing a hypothetical history of their navigation methods when there was probably a much better way - more suited to what the technology they had and involving a lot of ingeuity? I think one thing is certain and that is that they would have had an awful lot of failures; more than we would be prepared to accept these days. History does not record those failures.