Last week I drove this instrument and its owner home from CAMMAC. The instrument is a clavichord, an early keyboard instrument. It has a very quiet sound and was often used as a practice instrument as it would not be heard in concert except in very intimate rooms. I have heard it in concert - it is VERY quiet.
Here you can see a closer view. The strings are hit by a brass mallet as the key is depressed. You can learn more about it via the Encyclopedia Britannica.