* * * * * ‘ST ANDREWS, _1. Jan. 1673_. ‘SIR,—I received your of the 23rd of December last, and am glad to have the occasion to keep a correspondence with such a knowing person as ye ar. I have not had leasur at this time to satisfie you in your probleme, being drawn away all this afternoon with necessarie affairs: but with the nixt I shall doe my endeavour for I expect not to mak the calculation considerablie short, seing the nature of the question doeth not suffice it. Our bedal his book against Mr Sinclair is come out several weeks ago. No more at present, but being in hast and hoping that ye will be pleased to continue this new correspondence, I rest, ‘Your humble servant, ‘JAMES GREGORIE. ‘for Mr COLINE CAMPBELL.’ * * * * * His widow and orphans were granted a pension by Charles II. of £40 a year Scots in recognition of what Gregorie had done in Scotland. No one could be found suitable to succeed him in the Chair of Mathematics at Edinburgh. The authorities waited eight years before they made another appointment; and when the new professor came, he was also a Gregorie, a nephew of the late professor. His own son, too, held a chair, but that was in Aberdeen, and he was a professor of medicine. CHAPTER IV DAVID GREGORY, 1661–1708 ‘Tycho Brahe was also one who used the sword, not to cut into flesh and bone, but to build up a plainer way among all the stars of heaven.’—HANS ANDERSEN. David Gregorie was the third son of his father and name-father, the Laird of Kinairdy. He was born in a house without the port in the Upper Kirkgate of Aberdeen, where the tradition of his birth lingered, and was indeed cherished many a year after the boy had grown to manhood, and had left his grey birthplace for the richer lands of the South. The boy’s mother was, it may be remembered, Jean Walker, one of the Orchiston family, and the child was taught from his babyhood loyalty to the Stuarts and a passionate adherence to the episcopal form of church government and teaching, which he carried with him to the grave.