The Pirelli "Aries" is an early pneumatic speargun with a built-in air pump using the inner barrel and the spear as a pump rod. The spear had tools built into the ends to operate the switch in the rear of the gun that converts the gun to pumping mode, then switches it back to shooting mode. It takes a big push to enable the teeth on the switch to grab onto and rotate the oscillating rear valve and lock it open as in doing so you push the spear in deeper than for cocking the gun for shooting! As a forward latching gun it is pretty unique in the field of forward latching guns as it uses a line slide and a spear tail stop.
This particular gun was owned by spearfishing great Jack Prodanovich, you can see him here with master speargun builder, Prodanovich gun expert and metal sculptor John Warren. Jack never used the gun as it was given to him for his interest as many people sent Jack guns to run his eye over and pass judgement. As he had his own speargun line for which hopeful customers would join a queue running around the planet, Jack was not really interested in such quirky things, but he had it hanging on the wall in his workshop along with many of his own weapons built over a lifetime of diving. My duty was to interpret the gun for the education of others, but I had to get it working first when it seemed to not work at all. Anyway here it is and with it a copy of the fully annotated diagram that I sent back to Jack after some time studying and examining it.
Of course the gun is destined for a museum one day, I am just the temporary custodian. The gun has never been shot and has original everything just as the day that it was first sold. The only thing missing is the rear rubber line clip which has totally disintegrated with the passage of time. The gun never worked because the internal valve that depressurized it had been installed the wrong way around at the factory, so when you pumped in air it escaped just as quickly and it was lucky the gun was not thrown out as an unworkable idea from over enthusiastic Italians.
John and Jack holding the time worn, but totally unused Pirelli "Aries", a pneumatic gun from the days when they required frequent topping up with pressure as the early pneumatic spearguns were all slow leakers.