This could be an ancient scuba-diving suit https://crisisofdemocracticstates.blogspot.com/ Above the text is a strange picture from the medieval period, that portraits the person, who might dress in the diving suit, and is covered with the coagulate like silicone. This bite would help the diver get the extraordinary depth, while diving. The silicone would allow the diver to dive more safety because the bag of coagulate would protect the diver from the water pressure. The tube or hosepipe, what comes out from the mask might be filled with carbon, what allowed the diver dive more safety and longer period than the snorkel. Of course, that diving suit can be used in the many other things, but there is one very interesting mark in this picture. That is the knight's helmet and the purpose of that sign is tell, that this equipment is very hard stuff, and it was very needful information for soldiers and bodyguards, who saw the man wears this suite. But the diving equipment could...