As his sons and daughters grew up, Gregorie found it more and more impossible to get the quiet which he so much wanted for his work. His patients and his children between them were taking up all his leisure. In these circumstances he determined to rearrange his hours. He retired early to bed, and rising about two in the morning, worked for a few hours in the stillness of the night. When that was over, he went to sleep till he felt rested. If these nocturnal habits were known to the deputation that waited upon him, there was some excuse for their fears. What more alarming than the shadows in the room! The midnight crucible and the sulphurous smell were not there, but it must be admitted that the Laird of Kinairdy loved the hours of darkness better than the day. David Gregorie had twenty-nine children. Fifteen of them were the children of his first wife, and fourteen the children of his second. Nine of them died as quite little babies, but twenty grew to be older; and so, though everyone says, that it was remarkable for Kinairdy to have three sons professors of mathematics, it must be allowed that he had a most unusual number of children to choose from! In the pedigree of the family of Gregorie in Mr Philip Spencer Gregory’s book, from which the table of the professors is for the most part taken, it is seen that David, Professor of Mathematics in Edinburgh, and later of Astronomy in Oxford, Isabel, the grandmother of Professor Innes of Aberdeen, and James, Professor of Mathematics at St Andrews and Edinburgh, were the children of the first marriage; while Margaret, the mother of Thomas Reid, and Charles, Professor of Mathematics in St Andrews, were of the second marriage. Jean Walker was probably a cleverer woman than Isabel Gordon, Gregorie’s second wife. In the first place she converted her husband to Episcopacy and Toryism, and secondly, her son David was much the most brilliant of the Kinairdy children. To him it was, when he was working as Savilian professor at Oxford, that old Kinairdy confided a model of an improved cannon, which in his enthusiasm to improve the munitions of war, he had designed in his peaceful home by the Deveron. His son, who thought it most ingenious, showed it to Sir Isaac Newton, and the great philosopher evidently agreed with him; but to invent an instrument, the only object of which was to kill better than any cannon in use, seemed to him a fearful abuse of ingenuity. The horrors of Marlborough’s wars, where men were slaughtered by the thousand, were they not enough as it was? Who could deserve mercy from his Maker if he were to bid god-speed to such a terrible machine? Sir Isaac asked the professor to destroy the model, which he did, and the little toy which may have been a gatling gun, for aught we know, was broken in pieces.