So why didn't they decide in the first place to build this one outside too, to allow visitors to climb up on the tower themselves and use the armillary sphere to observe the stars and compare them with the celestial globe on the middle layer?
那當時何不也建在室外，讓觀眾親自上台，用渾儀觀察星象，再與中層的渾象相對照，不就更能印證古人的智慧了嗎？