These were taken at the RAF Museum.
This photo shows the Low Altitude Bomb Sight Mark IIA and the Equal-Distance Bomb Sight, and a Reversing Stop Watch. The plaque has this to expound about the latter: "One of the earliest bomb sights of British design to be used during the 1914-1918 war was the Equal-Distance (or Equidistant) Sight. This was developed by Warrant Ofc F W Scarff, RN and in 1915 was adopted by the RNAS.
This is the High Altitude Bomb Sight Mark 1A