13. O wheel--rather, "they were called, whirling," that is, they were most rapid in their revolutions [MAURER]; or, better, "It was cried unto them, The whirling" [FAIRBAIRN]. Galgal here used for "wheel," is different from ophan, the simple word for "wheel." Galgal is the whole wheelwork machinery with its whirlwind-like rotation. Their being so addressed is in order to call them immediately to put themselves in rapid motion.

JFB.