Wallis ranked Oughtred’s _Clavis_ and Hariot’s _Praxis_ very high, and because both were first printed in 1631, treated them as productions or inventions of that year, whereas Hariot’s method, as we have seen, had been long practically before his disciples; and was, ten years after the author’s death, given to the world avowedly as an’ accessory’ only, or preliminary treatise, that it ‘might suitably serve as a necessary preparation or introduction to the study of Hariot’s remaining works, the publication of which is now under serious consideration.’ Unfortunately this excellent scheme fell through, probably in consequence of the death of the Earl of Northumberland, and perhaps partly because of the death of Nathaniel Torporley who had long been engaged in ‘penning the doctrine’ of Hariot’s mathematical papers. They both died in 1632, shortly after the publication of the Praxis. Wallis’s charge had a basis of truth, but it was narrow and petty. As an Algebraist he seems to have lost sight of the main point, that Descartes’ great work was on Geometry and not on Algebra, and that Hariot’s method, though first printed in 1631, was almost as old as Descartes himself. Montucla the French mathematician, near the close of the last century, in his History of Mathematics, summed up the controversy raised by Wallis including the minor one raised by Dr Zach in 1785, clearing Descartes of Wallis’s charges and relegating Hariot to the respectability of a second-rate mathematician. If Montucla’s verdict be based on mathematical reasoning as loose and slipshod as is his statement of the historical points of the case, to say nothing of his utter ignorance of Hariot’s biography and true position as an English man of science, one feels justified in rejecting it as worthless : as one also is compelled to do the vapid conclusions drawn from Montucla which have since found their way into many recent biographical dictionaries and into many pretentious articles in learned encyclopædias respecting Hariot and his works. The truth seems to be that Hariot was unlucky and fell into oblivion accidentally. He was a man of immense industry and great mental power, but perhaps careless of his scientific and literary reputation. As has been seen, he always had many irons in the fire, and was overtaken by death in the prime of life, leaving, as his will shows, many things unfinished, and none of his papers in a state ready for publication. He was surrounded by the best of friends, but time and opportunity, as so often happens in the affairs of busy men, worked against him, and he was well nigh consigned to forgetfulness.