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compass of a few lines. Born in Glasgow, December, 1805, he passed first to a preparatory school, then to the High School, when he was nine years of age, and in 1819 to the University, where he remained seven years, taking his M.A. degree in 1826. Graham was originally intended for the Church, but strong predilections for a scientific career, especially as a chemist, caused him to shape out a path for himself, much to the grief of his father, a merchant of good position, who, not knowing much about the aims or scope of science, may have been prejudiced in his judgment. From Glasgow the young student proceeded to Edinburgh, where his scientific inquiries were carried on under Dr. Hope.

Graham's progress afterwards may be thus indicated:-Lecturer on Chemistry in the Mechanics' Institute; Professor in Andersonian Institution, 1830; succeeded Dr. Turner in Chemical Chair of University College, London, 1837; Chairman of Chemical Section, British Association (Birmingham), 1839; first President of Chemical Society of London, 1841; Master of the Mint, 1855. It was in Glasgow under the skilful teaching of Dr. Thomson, that Graham first applied himself to chemistry as a science, for, however much his boyish mind may have been attracted by the wonders of experiment, Dr. Smith believes that it was at a very early age Graham began seriously to consider the recondite laws of matter. In 1826 a paper was prepared by him on the absorption of gases by liquids, and his shrewdness and calm mode of speculation were as apparent at twenty-one as at any time of his after life. He supposed, for example, that absorption and liquefaction of gases are regulated by the same fundamental properties. Three years later (1829), he succeeded in demonstrating what has come to be known as Graham's Law-that the diffusion of gases is inversely as the square root of their density. Other rapid discoveries regarding the nature and movement of gases and liquids soon placed Graham alongside the foremost chemists of his day. In addition to many delicate experiments connected with the gold coinage, much time was devoted by the new Master of the Mint to the issue of a bronze coinage as a substitute for the once familiar

copper pieces.

When Graham died in September, 1869, the Mastership of the Mint was not filled up, the coinage Act of next year providing for the title passing to the Chancellor of the Exchequer for the time being, the practical duties connected with the office falling to be discharged by the Deputy-Master. In this way an end came to be put to an office which had been filled by the most illustrious men of science from the days of Sir Isaac Newton, who called in the vitiated coinage of his time, till Thomas Graham, who, in his own department of physics, was no way overshadowed by the universal fame of even the great astronomer. In addition to the text of the "Life," made up as indicated, there is an appendix in the shape of "Critical Remarks," written by Dr. Smith, and originally prefixed to the "Physical Researches of Thomas Graham," printed for private circulation eight years since by himself and Dr. James Young of Kelly. A photographic portrait conveys a pleasing impression of Graham's mild and retiring yet happy disposition, although even in these points it does not surpass Brodie's fine statue in our Square, where the seated figure of the great chemist (presented to the City by Mr. Young), and almost within earshot of that useful Institution where he filled his first professorial chair, fitly matches with Chantrey's wonderful delineation of the great engineer on the opposite or

western corner.


FORMING, as it now does, the basis for most surveys within Great Britain and the foundation also for all reliable maps, whatever scale it may be found necessary to use, the Annual Official Survey Report just sent out in the form of a Parliamentary Blue-book, suggests matter for reflection involving wider issues than the usual duty of simply noting what progress has been made with this great national undertaking. A hundred years (in 1884) has just run out since General Roy,

then a Colonel of Engineers, took the first real scientific step in the enterprise, by laying down, under command of His Majesty, the famous basis line of triangulation on Hounslow Heath. Little being known of General Roy earlier than what touches the busy middle-age portion of his life, time may not be thought lost in setting down a few words concerning an officer who was at once the foremost surveyor of his day, eminent beyond most in mathematical studies, and, so far as Scotland was concerned, the father of geodetic science. Our West Country has special reason for feeling proud of its connection with a scholar who would have been great had he done nothing more than initiate the Ordnance Survey and write "The Military Antiquities of the Romans in Britain." The son of an intelligent grieve, who combined the duties of factor with that of gardener on the estate of Hamilton of Hallcraig, Carluke parish, William Roy was born at Milton-head, 4th May, 1726. Carluke village at the time was in a state of chronic decay. Small as the place was in the early days of Charles II., a charter was obtained in the second year after the Restoration, erecting it into a burgh of barony under the name of Kirkstyle. Any improving influences that might be supposed likely to spring from such an increase of dignity would appear to have operated for only a short time, as at the birth of Roy the burgh comprised little more than the parish church, the manse, and a very few cottages. The population of the entire parish, ministered to in things spiritual by the Rev. James Dick, was not much, if anything, over 1,460. The latest census return (1881) gives the parish population at 8,552. In Roy's early days the working of iron and coal which has made the district so prosperous, and it may be even said famous, in the annals of industry was on the most limited scale. Even cotton weaving, which first raised the drooping fortunes of the place, was all but unknown. Only a very little is known concerning Roy's early education or pursuits. It may be surmised, however, in a general way that he devoted considerable attention to engineering studies before obtaining a commission in the army as lieutenant in or about 1741. His brother, Dr. Roy, was born in the same parish.

The Rebellion of 1745 first brought Roy into notice as an engineer and surveyor. After the "rising" had been stamped out in blood by Cumberland, at Culloden, in April of the following year, Government became more alive than before as to the necessity of exploring and laying open a country so difficult of access as the Highlands of Scotland. It was determined, therefore, to carry roads through the most remote recesses, and establish efficient military posts along the entire line. In this way it came about that the first methodical operations for a military survey of Great Britain took place at the distant point of Fort Augustus, in 1747. General Watson, Quartermaster-General to Lord Blakeney, was encamped in the fort at the time, and by this officer the Highland survey, afterwards known as "Cumberland's Map," was entrusted to his junior officer, Colonel Roy. Although the original intention would not appear to have embraced more than the Highlands, yet the surveyor gradually found his way into the Lowlands, and even along the more important coast lines. The field work was carried on in summer, and the drawings, on the scale of one inch and three-quarters to a mile, prepared during the winter in Edinburgh Castle. At the end of eight years the undertaking was advancing, but far from finished; and when it was then suspended, Colonel Roy admitted that the survey, having been carried on with inferior instruments, and the sum allowed very inadequate for its proper execution, it ought rather to be looked on as a fair military sketch than an accurate map of the country. The breaking out of the war in 1756-a war waged against France in America, in India, and on the high seas-scattered the surveyors, and called away from Scotland such engineers and foot soldiers as could be spared. The Highlands for the time being crushed into peace, the survey drawings were consigned to the Royal Library, unusually rich in such collections, as any one may see by a glance at the formidable row of cases in the British Museum, and there they lay, almost neglected, while geographers like Ainslie were making private independent surveys, instead of perfecting, as they might have done, the work of Roy. Even in the face of colonial troubles the scheme of a national survey was brought up in Parliament from time to

time; and at length, in 1763, Government undertook to propose a money vote in aid. Yet even preliminaries were not finally settled for twenty years, or in 1783, when Roy was engaged in measuring on his own account a base of 7744°3 feet across the fields between the Jewsharp, Marybone, and Black Lane, near St. Pancras, as a foundation for a series of triangles carried on at the same time, for determining the relative situations of the most remarkable steeples, and other places in and about London, with regard to each other and the Royal Observatory at Greenwich. Some little time before this a correspondence had been going on between the Count d'Adhemar and Mr. Fox as to the advantage which would accrue to astronomical science by carrying a series of triangles from the neighbourhood of London to Dover, there to be connected with the triangulation already executed in France. The King approved of the design, and agreed to share the cost with the Royal Society, that body having taken a lively interest from the first in all the proceedings. Roy was thereupon summoned to Windsor, and instructed by the King to commence the survey. His first step was the measurement of that now historical base-line on Hounslow Heath (5.19 miles) -measurements, it has been found, so careful that no essential error has been discovered by the most rigid scrutiny of modern surveyors. The great threefoot theodolite, constructed for the occasion by the optician Ramsden, after being carried up the highest mountains, placed on the pinnacles of our loftiest churches, and shipped to distant islands, is still in daily use, and as perfect as when it left the hands of its cunning constructor. Ramsden, indeed, made his instrument something more than a theodolite. It is also a quadrant and transit instrument, and capable of measuring horizontal angles to fractions of a second. To the same ingenious optician is also due the invention of the survey measuring chain, superseding at once the varying deal-rod, and rivalling even the glass-rods as a measuring line.

The importance of the base-line in triangulation, for the purpose of calculating unknown distances, is stated with as much simplicity as the subject permits, by the writer of an article on the "Cadastral Survey" in the "Edinburgh Review,"

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