Dickson's method for generating Pythagorean triples --- did him show/proove how he obtained his formulas?

Question

https://en.wikipedia.org/w/index.php?title=Formulas_for_generating_Pythagorean_triples#Dickson%27s_method

As in the title. Or does anybody did it? Thanks in advance for your replies.

Answer 1

Alright, page 169 in volume II of his History. He published it in the first year of the American Mathematical Monthly in 1894. Apparently that article was a single page, perhaps it was in the form of a letter. Dickson then lists four people who found the same description later, published 1897, 1901, 1908, 1916.