This card may show a canal in Finland, but it also demonstrates, exceedingly well, what happens in a lock. If you look at the card, you will see that there is the rigging of a tall ship right at the line of horizon. Now that is on a river or waterway all its own. but it has halted and and come to the gate. Pretty soon, the gates will open, the ship will come in along with some of the water from the top level, and the gate behind it will close, leaving the ship in a compartment.Then the front gates will slowly open and the water and the ship will come down until it is level with the next compartment, and can sail into it. Then the procedure will be repeated until it reaches the level of the canal we can see at the bottom.
The canal on this card is said to be at Saima. Now that could be the French spelling, or it could be an error, because today we know the canal as the Saimaa Canal, with two final "a"s. It enables ships to travel from Lake Saimaa to the Gulf of Finlanda, via the city of Vyborg, and it is both the best known and the most important canal in the country, some forty three kilometres long with eight locks, three of which are in Finland and five of which are in Russia. Construction of the canal began in 1845 and it was opened on September 7, 1856.