Over the following years I managed to slowly acquire the various parts to complete the set of apparatus. However the apparatus shown here has a ‘replica’ regulator back-pack. The hose shown on top of the helmet at to the right of the diver is the speaking tube: in 1874 Auguste Denayrouze’s brother Louis Denayrouze, patented this system which is simply a tube (identical to an air-hose) with a membrane on either side. The membrane inside the helmet covers a large part of the back and top of the helmet, so when the diver speaks to the surface assistant his voice can be heard through the membrane at the tender’s end of the speaking tube. The diver can also hear the tender when he speaks from his end. To date, I have not been able to find the exact date when the second model ‘Pompe Hydraulique’ air-pump was introduced, but it was probably around 1870. The difference between the ‘first model’ air-pump and the ‘second model’ is the shape of the cylinders: the early pump has cylinders with a ‘bell shape’ top, while the second model has flat top cylinders. The pump used with the ‘pig-snout’ mask apparatus by the Danish Navy is of the second model and it has the company name ‘Rouquayrol-Denayrouze’ cast into the iron base plate. Most pumps of this second model only have the name ‘Denayrouze’ casted into the base plate. Photographs, David L.Dekker
In the photographs below, the ‘regulator’ back-pack has been replaced by a normal lead weight and the air-hose has been connected directly to the helmet for diving use as a ‘ventilated’ (free flow) system.