Wow so this is a beautiful gamba roundback instrument made in the mid 19th Century in eastern Europe, and is likely Saxon or Bohemian. 

The back and ribs are made from gorgeous maple with bold, even  flame under a dark brown varnish. Ribs are quite deep, ensuring a powerful low-end voice. The bass has a stylish Bresque Basses C extension in solid ebony, has an adjustable neck, and inside, is fitted with a powerful Lamarre style bass bar.

42" String length, D neck. Currently has Kaplan strings.

The bass has a dark, smooth voice and plenty of it.

This is a superb instrument that would be at home in any contemporary professional orchestra.