Riddle

A waggon, squarely-built and strong,
Runs swiftly on twelve wheels, and has for ages borne along
Two and fifty ladies, set in order on it one and all.
The waggon never halts nor slacks,
But presses swiftly onwards in its own appointed tracks.
It is not hewn of wood, 'tis not too short, too long, too broad, too small.
With constant toil 'tis drawn, where'er its course is,
By seven white and seven sable horses.
Who will tell me now the meaning of this waggon?
God grant that man a happy year!
The waggon has been told you here.
It runs on till its master puts the drag on.