I spotted this stone in the wall of a building on Buitengracht Street, and just had time to snap a photo through the window before the traffic light turned green and I had to pull away again.
I did a little bit of sleuthing, and have deduced that the inscription must refer to the Mission School that was attached to St Paul's Church back in the 19th century. According to the website of St Paul's Anglican Church, the foundation stone of the Mission School was indeed laid in 1899. If anyone knows any more about the school, please leave us a comment.