at interval

The chain has at intervals disks or lifts which fit the tube through which the ascending part passes and carry the water to the point of discharge.

a curtain of fabric draped and bound at intervals to form graceful curves n

n a curtain of fabric draped and bound at intervals to form graceful curves n an embellishment consisting of a decorative representation of a string of flowers suspended between two points

at intervals.

n the act of combining one thing at intervals among other things