John Howkins Antiques has dated this piece to the 1850s.

This type of table is usually found in oak or mahogany and is particularly unusual in walnut.
The sliding top lends this table for other uses when not reading.
More pictures available.
Width 36" ... 91.5cm
Depth 17.75" ... 45cm
Minimum height 30" ... 76cm
Max adj. height 42" ... 107cm
Fabulous colour and condition.
John Howkins Antiques has dated this piece to the 1850s.
You can view the stock and full dealer information on the John Howkins Antiques Profile Page