What are center holes?

Some articles on center holes, hole, holes:

Tinkertoy - Standard Parts
... Like spools, their center holes have a snug fit ... pieces with a single blind axial hole snugly fitted to the rods ... approximately 2 inches long and half an inch in diameter, with snug-fitting blind-drilled holes in either end, and a loose-fitting through-drilled hole crosswise through ...

Famous quotes containing the words holes and/or center:

    And as my wit doth best devise,
    Love’s dwelling is in ladies’ eyes,
    From whence do glance love’s piercing darts,
    That make such holes into our hearts;
    And all the world herein accord,
    Love is a great and mighty lord;
    George Peele (1559–1596)

    Every beloved object is the center point of a paradise.
    Novalis [Friedrich Von Hardenberg] (1772–1801)