[raaaid]

oh thanks a lot this is the easiest method to obtain longitude:

make a gruesome clock that can be even moved arbitrarily by hand with two exact COUNTEROTATING NEEDLES

you align it west east and count how many times each needle crosses the sun(thanks a lot ; thats the xterior reference point)

after a whole travel around the earth one needel will have crossed the sun one more and the other one less however the beat of the clock

i bet this is how the ancients conquered the pacific islands

edit:

imagine an ancient hawaian obtaining longitude:

the magic wheel in which two needles are countergeared

he is instructed to spin them 100 times per day as he travels

he knows that if he is still since one is following the sun and the other has opposite sense each day he will count one more of one than the other crossing the sun, so each day he adds one to one and substarcts one to the other

but if he travels 80 sunsets around the earth he will count 8001 of one needel crossing the sun while 7999 of the counterneedle crossing the sun while if he had not moved in 80 days would have counted 8000 of both exactly