The development of the submarine weapon was a product of many different minds, all with varying intentions. Some were patriots, seeking the ultimate counter to the naval super-weapons of first-rate powers. Others were schemers, betting their lives and fortunes on unproven vessels of their own design, seeking riches and renown beyond measure. There were, of course, those who explored the physical universe through the mind, men who could conceptualize the vastly complicated interaction of man-made materials and the physical nature of the abyss. These men oftentimes never sought to bring their drawings and writings from the confine of paper or parchment, but inspired generations of dreamers to follow. The most important group, however, was that of the journeyman inventor, men of the mind who traveled from country to country seeking patronage for their radical dreams.
Though their experiments existed nearly a century apart, Frenchman DeSon and rural English carpenter Nathanial Symons were both inspired by the thinkers and dreamers of previous generations. In 1648, DeSon attempted to create a spring-powered internal paddle-wheel submarine based on a book written by English writer Bishop Wilkons. It is not known if DeSon ever tested his device (and a good thing too, as it employed several technical solutions to submarine design problems that have never been demonstrated to be effective), but it did seem to have been popular as an attraction in fairs and markets.
A century later, Nathanial Symons seemed to have been more successful in his endeavor. He demonstrated his vessel, inspired by the drawings of Abbe Giovanni-Alfonso Borelli (and published in the De Motu Animalium in 1680) in the River Dart to the stares of several hundred captivated observers. Though it seems that the test itself was successful in as much as it did not kill Symons, he promptly disappears from the historical record, and no mention is given to what became of his invention.