Who are some forgotten mathematicians? [closed]

In Thomas' Calculus, he presents ''Nicole Oresme's Theorem'': $$ \sum_{n=1}^\infty {n\over 2^{n-1}}=4. $$ My first reaction was "who is this person?''. As it turns out, he was a Frenchman from the $14^{\rm th}$ century (!) who produced an astounding number of deep results. In addition to the previously mentioned result concerning infinite series, he proved results for geometric sums and was the first person first to show that the Harmonic series is divergent. In addition to this, he anticipated results of Galileo, Descartes (the idea of analytical space), and Cantor (cardinality) (see the above link and here.

I'm astonished, and perhaps should be ashamed, that I had not known of him before.

So, my question is: who are some other people who have lapsed into obscurity but deserve to be remembered?

Solution 1:

There is the Stigler's law of eponymy which says that "No scientific discovery is named after its original discoverer." So, there are lots of mathematicians who have lapsed into obscurity.

Solution 2:

Joseph Raphson developed what is probably the most important algorithm in applied mathematics.

Today, most people know it only as "Newton's Method."