The lift lock was opened in 1904, and has been lifting and lowering vessels up and down the waterway ever since. The lock has two identical ship caissons (in other words "bathtubs" holding water only a few feet deep) in which vessels are taken up or down a journey of 19.8 m (65 ft), the highest hydraulic boat lift in the world.
Each caisson is filled with water and the boats enter, tie up to the rails, and the gates of the caissons are closed. The lift lock functions by gravity alone using the counterweight principle. One caisson always ascends and the other always descends during each locking cycle. There water level is a bit higher in the upper caisson making it heavier, so as the top one carries boats to the lower water level, the lower one ascends.
Heading towards the lift lock. We're going to go up in the left caisson.
The black pillar is the hydraulic cylinder that supports the caisson, and allows the heavier caisson to push the lighter caisson upwards. Once the boats are secured and the gates are closed, the crossover valve is activated and the action begins.
The "Lady Catherine" was on her way down as we were going up. Lots of waving going on as we crossed over.
And the view from the top as we were on the return journey. This boat was going up and we were going down. Lock 21 is rumoured to be haunted by a woman who was burned for being a witch in the 1840s and/or a worker who was killed during it's construction.... or a pair of starcrossed lovers.... take your pick.... details here. (There's also some pics of the lock construction at the same link.)
Went down by Ogemah, got off at old Chemong Station where met by rig & drove across to Lakefield by 9:45 am. Got on Empress there & went down with her & 'Stoney Lake' to No. 5 dam where Parliamentary party after lunch['ing' has been crossed out](in big tent there) boarded the two boats about 1:30 pm & proceeded down (in pouring rain) to Lift Lock which was formally opened by both boats being let down at 2:30 pm..."