What in the world are all those extravagant circular lines that almost cover the signature of Manuel Aflague?
All those flourishes are called the rúbrica in Spanish, and they were a common feature of Spanish (and Chamorro) signatures in the 1800s.
The point of it was this : it is far easier to forge a person's first and last names. But it is harder to forge the rúbrica. One's first and last names were limited to the letters that spell those names. Far more open to one's personal artistic whims was the rúbrica. Therefore, it was the rúbrica that assured others that the signature was authentic.
It was said that a rúbrica without a signature was worth more than a signature without a rúbrica.
So common was it that it was more surprising to see a signature without a rúbrica than an I without a dot or a T without a cross.
In many cases, a signature was not legally valid without a rúbrica.
So, those Chamorros who could sign their names copied the Spanish custom of designing a rúbrica to accompany the signature.
Here are some examples :
Andrés de Castro
Some said that the rúbrica was like the snakes on Medusa' head.
They could puzzle even the devil in discovering where they began and where they ended.
But they all agreed that it was downright impossible to reproduce the rúbrica as well as the inventor, so it was a seal of authenticity better than any.