The locks are used whenever the utmost strength is absolutely necessary.

To remain competitive, the company increased the hours when locks could be used, until by 1830 they were available 24 hours a day.

At others the locks were never used and the keys were lost.

This lock is used in doors and locks for boxes.

The gates allow the lock to be used at most states of the tide.

The locks were obviously well used, and the next two followed shortly.

The old lock is still present, but is no longer used.

The lock could be used with only fifteen minutes for pumping instead of four hours.

Now their condition is so precarious that the locks can be used only by special arrangement.

This lock has been placed in caretaker status and is no longer used.