A boxed Sikes hydrometer with an inlaid label to the front.  The label says'Sikes HydrometerDring & Fagemakers to H M customs & Exciseof the united Kingdom & colonies & Stamford Street London. They were a long established company starting in London in 1790 and continued trading upto the 1960s. This box dates from around 1905.
Inside it comprises of a  glass cylinder, a weighted bulb with scale, a small magnifying glass, a thermometer and a set of 10 small brass loop weights sitting on pegs. Each has its own compartment within a wooden box lined with velvet.  
Hydrometer sets were used to determine the specific gravity or "heaviness" of a liquid./alcohol.
Unusual to find such a complete set.