Spanning from 1714 to 1830, The era of the Hanoverian Kings.
The particular design, of two vertically sliding frames counter balanced by weights, within this Georgian time frame became very popular. Decorated with thin glazing bars sectioning the sashes typically into six single glazed panes each.
Although the word sash comes from the french word chassis meaning frame, there is little historical use of this counter balanced system being used in France.
Many historians believe that the rise of the sash window was helped due to Robert Hooke, a London surveyor after the Great fire of London in 1666 who was also the architect of Ragley Hall in Buckinghameshire where the creation of the counter balanced (sliding sash) was used.
A year after the Great fire of London a new building act was enforced stating that all windows need to be four inches deep into the building from the face of the brickwork. Sliding sash windows were then used to conform to this new regulation with the ventilation benefits of being able to have the sash only slightly open - without hindering the security of the dwelling. Also the metal work of the window was hidden away inside the framework box behind the brickwork out of the way of the typical English weather elements. The increased span of the glazing allowing more sunlight into a room and was no surprise that this design of window was so prevalent during the times of the King Georges.