Susie Siegel, age 8, of Utica, N.Y., for her question:

HOW DOES A CANAL LOCK WORK?

A canal is a man made waterway that connects two bodies of water. If the water is at the same level in both locations, only the channel is needed. At times, however, one body of water is higher than the other. When this happens, the canal will need special chambers called locks.

A lock is a concrete chamber with watertight gates at either end. Eight locks are needed on the Welland Canal to move boats down 325 feet from Lake Erie to Lake Ontario. The boat enters a lock. The doors at each end of the chamber are closed and water is then pumped out to lower the ship to the level of the next section of canal. After traveling 27 miles and having the doors closed on eight locks, the boat has reached the lower lake's level.