He also discovered methods of solving equations of degree four which were similar to those which Harriot had found but Wallis claimed that he made the discoveries himself, not being aware of Harriot 's contributions until later.
Siya rin ang natuklasan pamamaraan ng solving equation ng mga apat na antas na kung saan ay katulad sa mga na Harriot had natagpuan ngunit Wallis inaangkin na ginawa niya ang kanyang sarili discoveries, hindi malaman ng Harriot 's kontribusyon hanggang mamaya.