The hypothetical "top" and "bottom" of the Earth (better explained in OP)

[Lumpy]

Placing the IDL in the Pacific also is perhaps relevant to the “go east or go west from Europe” question I posited here:

When East meets West (by sea)

When going by sea from Europe, you would obviously go east to go to Africa, the Middle East, India, Indonesia and probably Australia and China. If you were going to the Americas and possibly as far west as Hawaii, you would go west. If you wanted to go to Fiji- ??? Pure geography might not be the criterion because of things like favorable winds and currents, available ports, stops for other purposes along the way, maybe the time of year, etc. And obviously the introduction of steam and the openi…