Figure 19. Hirondelle locking sounder. Prince Albert I of Monaco designed this
apparatus in 1888. His idea was to modify a Baillie or Travailleur sounder by
replacing the various valves with a spigot which closed after sediment entered
the tube. The engineer Jules le Blanc built this instrument for Prince Albert.
It was used sucessfully in 1888 off the Azores in depths of 600 to 2000 meters.