That globe is massaged into greater roundness between heavy plates and honed to exact sphericity and smoothness by rolling through grindstones hundreds, if not thousands, of times [see main illustration, right].
That globe is massaged into greater roundness between heavy plates and honed to exact sphericity and smoothness by rolling through grindstones hundreds, if not thousands, of times [see main illustration, right].
将小球放在重盘之间滚压得更圆，同时在砂轮间滚转数百次到数千次，打磨得更圆更光滑（见右图）。