Just at this time, the invention of logarithms, by a Scotch laird, John Napier of Merchiston, near Edinburgh, was becoming known in the then comparatively restricted scientific world. Logarithms are prepared tables of numbers, by which complex problems in trigonometry, and the tedious extraction of roots, can be performed by the simpler rules of arithmetic. To the well-educated, they save much time and labour; in the art of navigation, they enable the mariner who may be unskilled in mathematics, to work out the most intricate calculations. In all vessels on the open seas, when observations can be taken, in all mathematical schools and astronomical observatories, logarithms are in daily use. As with other things, familiarity discounts our wonder at their aptitude and value; but the estimate by scientists of Napier’s invention is, that it ranks amongst British contributions to science, second only to Newton’s _Principia_. Kepler regarded Napier as one of the greatest men of his age; and in the roll of those who were foremost in establishing real science in Europe, his is the only name which can be placed alongside the names of Copernicus, Tycho Brahe, Kepler, and Galileo. The long sloping street called the Canongate, which reaches down from the centre of the Old Town to Holyrood, was, with its tributary lanes and closes, created a Burgh of Regality by King David the First. It was outside the walls of Edinburgh, and had its own Council of Bailies, Deacons of Trades, and Burgesses. The Canongate is full of old memories. There is the house of John Knox, the sturdy Reformer and typical presbyterian. There is the Tolbooth—the Heart of Midlothian. From the balcony of that old mansion, called Moray House, a gay party were, in 1650, with malicious and triumphant eyes, looking down upon a crowd through which was slowly wending a low cart, in which was ignominiously bound down that spent thunderbolt of war, Montrose—he is on his way to execution. Aye, but in after years two in that jubilant party—Argyles, father and son—will both also pass up that street amidst jeering crowds, and to similar fates. ------------------------------------------------------------------------ [Illustration: THE CANONGATE TOLBOOTH.] ------------------------------------------------------------------------