This change of occupation, and the success that crowned it, required a correspondent change of study; and accordingly Mr. Stevenson, throwing aside his Latin, which he had only half mastered, and turning away from Greek, which he had not yet entered, began to devote himself to the exact sciences. Opportunities, indeed, there were comparatively few, on account of the active life which he had commenced at an early period; but such as he possessed he improved to the uttermost. In this way, while superintending the erection of the lighthouse at Cumbrae, he availed himself of the cessation of the work during the winter months, by attending the Andersonian Institution at Glasgow, where he studied the mathematical and mechanical sciences connected with his profession. Here, he had for his preceptor, Dr. Anderson himself, the honoured founder of the institution, of whose valuable instructions Mr. Stevenson ever afterwards retained an affectionate remembrance. He pursued the same course of improvement in his education while employed by Mr. Smith in the erection of lighthouses on the Pentland Skerries in Orkney, so that as soon as the labours of each summer were ended, the winter months found him in close attendance at the classes of the university of Edinburgh. In this way he completed, during the course of several sessions, a curriculum that comprised mathematics, natural philosophy, chemistry, and natural history, to which he added logic, moral philosophy, and agriculture. It was the same perseverance at work which struggled for a foundation upon the living rock amidst the battling of waves and tempests, and having found it, persisted in adding stone to stone, until a stately tower was erected, and a guiding light kindled upon its summit. He thus became not only an accomplished scientific scholar, but also a student of considerable literary attainments, while he was employed the greater part of each year in contending with the stormy seas of the Orkneys, and dwelling upon their bleak islets and solitary shores. His first tour of inspection as superintendent of lighthouses, was made in 1797, for which year he drew up the annual report for the Board of Commissioners; and during his long tenure of office, that extended over half a century, twenty-three lighthouses in the district of the Commission, which he designed and executed, attested his unwearied diligence, as well as professional skill. Many of these were constructed in situations that tasked the utmost of scientific knowledge and anxious study, while the successive steps of improvement which they exhibited, evinced the fresh ardour with which he had advanced to every undertaking, and the earnestness he had felt that each should prove the fittest and the best.

But the great work of Mr. Stevenson’s life, and the durable monument of his professional attainments and success, is to be found in the Bell Rock lighthouse, of which he published such a full and interesting account in 1824, in one volume quarto. This rock, a sunken reef in the Firth of Forth, situated in west longitude from Greenwich 2° 22’, and in north latitude 56° 29’, and composed of red sandstone, was found so dangerous to navigation, that attention had been called to it at an early period, and, according to tradition, a remedy was adopted to warn mariners from the dangerous spot, by a humane abbot of Aberbrothock. This was a bell, erected upon the rock, and so connected with a floating apparatus, that the action of the winds and seas caused the bell to toll over the uproar of the waves amidst the darkest weather. And thus, as the well-known ballad of Southey informs us—

The popular legend adds, that a pestilent pirate, the enemy of God and man, in a mere spirit of wanton mischief, silenced the ocean monitor, by taking down the bell, and throwing it into the sea. But poetical justice was not long in overtaking him; for only a year after, while pursuing his vocation in the same dangerous sea, his ship in the dark drifted upon the now silent rock, and went down, with the captain and all hands on board; while,

The work was commenced by searching for such a vessel as would serve for a temporary lighthouse, as well as a habitation for the workmen. This was soon found in a Prussian fishing-vessel of 82 tons, one of the captures of the war, which being rounded off both at stem and stern, was best adapted by its form for the new service in which it was to be employed. After having been suitably fitted up and rigged, this Pharos, as it was now named, was furnished with a large copper lantern for each of its three masts, and moored near the Bell Rock. Another vessel, expressly built for the purpose, called the Smeaton, of 40 tons, was employed in bringing the stones for the building, that were hewn in the quarries of Rubeslaw near Aberdeen, and Mylnefield near Dundee, and conveyed to Arbroath, the nearest harbour to the rock. The work itself was commenced on the 18th of August, 1807; and such was the clink and bang of hammers, the hurrying of feet, and the din of human voices that now took possession of the solitude, that the affrighted seals, which had hitherto regarded the Bell Rock as their own exclusive property, went off in shoals in quest of new settlements. It is not our purpose to detail the daily, and almost hourly difficulties with which Mr. Stevenson had to contend in a task of seven years’ duration, and the dangers to which he was exposed, while he had to battle with an almost impracticable foundation, and the continual war and shifting of elements that opposed every step of his progress. On one occasion, when the Smeaton was drifted out to sea, he was left with thirty-two workmen upon the rock, which, by the progress of the flood-tide, would soon be submerged at least twelve feet, while the two boats which they had at hand could have carried off little more than half of the company—after perhaps a life-and-death struggle with their less fortunate companions. At this critical moment he thus describes their situation, in the third person: "The writer had all along been considering various schemes, providing the men could be kept under command, which might be put in practice for the general safety, in hopes that the Smeaton might be able to pick up the boats to leeward when they were obliged to leave the rock. He was, accordingly, about to address the artificers on the perilous nature of their circumstances, and to propose that all hands should unstrip their upper clothing when the higher parts of the rock were laid under water; that the seamen should remove every unnecessary weight and incumbrance from the boats; that a specified number of men should go into each boat, and that the remainder should hang, by the gunwales, while the boats were to be rowed gently towards the Smeaton, as the course to the Pharos or floating light lay rather to windward of the rock. But when he attempted to speak, his mouth was so parched that his tongue refused utterance, and he now learned by experience that the saliva is as necessary as the tongue itself for speech. He then turned to one of the pools on the rock, and lapped a little water, which produced an immediate relief. But what was his happiness, when, on rising from this unpleasant beverage, some one called out ‘A boat! a boat!’ and on looking around, at no great distance, a large boat was seen through the haze making towards the rock. This at once enlivened and rejoiced every heart. The timeous visitor proved to be James Spink, the Bell Rock pilot, who had come express from Arbroath with letters. Every one felt the most perfect happiness at leaving the Bell Rock this morning, though a very hard and even dangerous passage to the floating light still awaited us, as the wind by this time had increased to a pretty hard gale, accompanied with a considerable swell of sea. The boats left the rock about nine, but did not reach the vessel till twelve o’clock noon, after a most disagreeable and fatiguing passage of three hours. Every one was as completely drenched in water as if he had been dragged astern of the boats." During the two first seasons occupied on the Bell Rock, Mr. Stevenson’s abode was the Pharos or floating light, as uncomfortable as well as perilous a home as the worst hulks which justice could have devised for the taming of a sturdy malefactor. Sometimes they had to ride out a gale, and endure all the horrors that precede a shipwreck, without the consolation of feeling that a voyage was in progress, or a port at hand into which they might run at the worst. On one occasion, indeed, after a storm, they found themselves making a voyage in sad earnest, with the prospect of being dashed against the Bell Rock by way of termination—for the Pharos had broke from its moorings, and was drifting, none knew whither. Even in fair weather, it rolled like a tub, or rather like a barrel, so that such rocking was provocative of anything but tranquil repose. After the beacon or barrack was erected, Mr. Stevenson took up his abode in it; but here the matter was not greatly amended, as this habitation was nothing more than a sort of pigeon-house edifice, perched on logs, and exposed to the onset of every wave, while the tide in calm weather rose upon it to the height of sixteen feet. Let the following description of a few hours spent in it suffice:—"The gale continues with unabated violence to-day, and the sprays rise to a still greater height, having been carried over the masonry of the building, or about 90 feet above the level of the sea. At four o’clock this morning it was breaking into the cook’s berth, when he rung the alarm-bell, and all hands turned out to attend to their personal safety. The floor of the smith’s or mortar gallery was now completely burst up by the force of the sea, when the whole of the deals and the remaining articles upon the floor were swept away, such as the cast-iron mortar-tubs; the iron hearth of the forge, the smith’s bellows, and even his anvil, were thrown down upon the rock. The boarding of the cookhouse, or story above the smith’s gallery, was also partly carried away, and the brick and plaster-work of the fireplace shaken and loosened. At low water it was found that the chain of the movable beam-crane at the western wharf had been broken, which set the beam at liberty, and greatly endangered the quay ropes by its motion Before the tide rose to its full height to-day, some of the artificers passed along the bridge into the lighthouse, to observe the effects of the sea upon it, and they reported that they had felt a slight tremulous motion in the building when great seas struck it in a certain direction about highwater-mark. On this occasion the sprays were again observed to wet the balcony, and even to come over the parapet wall into the interior of the light room. In this state of the weather, Captain Wilson and the crew of the floating light were much alarmed for the safety of the artificers upon the rock, especially when they observed with a telescope that the floor of the smith’s gallery had been carried away, and that the triangular cast-iron sheer crane was broken down. It was quite impossible, however, to do anything for their relief until the gale should take off."

Such is but a specimen of the obstacles encountered and the toils endured in erecting that wondrous edifice, the Bell Rock lighthouse. It was completed in December, 1810, and since that period it would be difficult to estimate the benefit it has conferred in that dangerous sea on the ships of every nation, which, but for its guidance, would have been dashed upon the rock, or wrecked on the neighbouring shore. There, from night to night, its lamp has continued to shine like a guiding star; while in snow and haze, its bell is heard as a warning voice through the thick atmosphere, when the light is obscured, or so dim, that its meaning is unintelligible to the bewildered navigator. Not fully four years after it was finished, when Sir Walter Scott made that well-known cruise among the northern seas, which he has entitled in his diary, "Voyage in the Lighthouse Yacht to Nova Zembla, and the Lord knows where," he thus describes the edifice, at that time still fresh in early youth, and regarded with all the pleasure of a startling novelty.

The whole diary of this voyage in the northern seas, which the great poet and novelist has fully detailed, abounds with incidental notices, in which Mr. Stevenson’s amiable disposition, as well as remarkable professional ability, diligence, and enterprise, are strikingly exemplified. It was one of those periodical voyages which Mr. Stevenson was wont to make in the erection of lighthouses, and the superintendence of northern lights; and besides three commissioners of the board, there were three pleasure tourists, of whom Sir Walter was one. The vessel in which they sailed was the lighthouse yacht, of six guns and ten men; for besides the storms of the Atlantic, lately a brush with a French cruizer, and even now with a Yankee privateer, might be no improbable contingency. The singular coasts that had to be surveyed, the strange places to be selected for the erection of lighthouses, and the difficulties that had to be overcome in such erections, will be best understood from the following quotation, which, therefore, notwithstanding its length, we give without curtailment:--

"Auqust 27, 1814.—The wind, to which we resigned ourselves, proves exceedingly tyrannical, and blows squally the whole night, which, with the swell of the Atlantic, now unbroken by any islands to windward, proves a means of great combustion in the cabin. The dishes and glasses in the steward’s cupboards become locomotive—portmanteaus and writing-desks are more active than necessary—it is scarce possible to keep one’s self within bed, and impossible to stand upright, if you rise. Having crept upon deck about four in the morning, I find we are beating to windward off the Isle of Tyree, with the determination on the part of Mr. Stevenson that his constituents should visit a reef of rocks called Skerry Vhor, where he thought it would be essential to have a lighthouse. Loud remonstrances on the part of the commissioners, who one and all declare they will subscribe to his opinion, whatever it may be, rather than continue this infernal buffeting. Quiet perseverance on the part of Mr. S., and great kicking, bouncing, and squabbling upon that of the yacht, who seems to like the idea of Skerry Vhor as little as the commissioners. At length, by dint of exertion, came in sight of this long ridge of rocks (chiefly under water), on which the tide breaks in a most tremendous style. There appear a few low broad rocks at one end of the reef, which is about a mile in length. These are never entirely under water, though the surf dashes over them. To go through all the forms, Hamilton, Duff, and I resolved to land upon these bare rocks in company with Mr. Stevenson. Pull through a very heavy swell with great difficulty, and approach a tremendous surf dashing over black pointed rocks. Our rowers, however, get the boat into a quiet creek between two rocks, where we contrive to land, well wetted. I saw nothing remarkable in my way, excepting several seals, which we might have shot, but, in the doubtful circumstances of the landing, we did not care to bring guns. We took possession of the rock in name of the commissioners, and generously bestowed our own great names on its crags and creeks. The rock was carefully measured by Mr. S. It will be a most desolate position for a lighthouse—the Bell Rock and Eddystone a joke to it, for the nearest land is the wild island of Tyree, at fourteen miles’ distance. So much for the Skerry Vhor."—It is only necessary to add to this amusing sketch, that the lighthouse contemplated by Mr. Stevenson was erected in 1842, by Mr. Alan Stevenson, his son, and successor in office, who in this difficult undertaking not only followed his father’s instructions, but emulated his perseverance and scientific ability.

During the long course of Mr. Stevenson’s professional labours, his calm calculating sagacity, and adaptation of means at once simple and effectual to an end that seemed unattainable, or not to be attained without the most complex agencies, were conspicuous to the last; and although not himself an inventor, he could largely improve on the inventions of others, and turn them to the best account. It was thus that the Eddystone lighthouse suggested to him the bolder and more difficult undertaking of that on the Bell Rock; while his plan of the jib and balance-cranes, and the changes which he adopted in the masonry of the building, especially in the laying of the floors, so that their stones should form part of the outward wall, were important improvements on the plans of Mr. Smeaton, whom he still was proud to call his master. The best mode of lighting these ocean lamps was also a subject of his inquiry; and the result was, his invention of the intermittent and the flashing lights, the former suddenly disappearing at irregular intervals, and the latter emitting a powerful gleam every five seconds—a mode of illumination distinct from that of the ordinary lighthouses in the same range, and admirably suited for the dangerous navigation of narrow seas. For the last of these inventions he was honoured with a gold medal from the king of the Netherlands. While his scientific anxiety and skill were thus devoted to the improving and perfecting of those buildings upon which the safety of navigation so much depends, he did not overlook the welfare of those to whom the superintendence of their bale-fires is committed; and his humane regulations, by which the comforts of these self-devoted prisoners of the ocean pillars were promoted, as well as his rules of discipline, by which their duties were simplified, introduced a marked change for the better into the dreary life of those upon whose watchfulness and fidelity so vast an amount of human happiness is at stake. Mr. Stevenson, indeed, may justly be said not only to have created the lighthouse system of Scotland, where it was so much needed, but to have brought it also to that state of perfection in which it has become the model to other maritime nations.

Independently of his duties connected with northern lights, Mr. Stevenson, in his general capacity as a civil engineer, was frequently a co-operator with Rennie, Telford, and the other chief engineers of the day. He also, after the peace of 1815, was the principal adviser in the construction of those new roads, bridges, harbours, canals, and railways, towards which the national energy and capital were now directed. Even the beautiful approach to the city of Edinburgh from the east, by the Calton Hill, was planned by him, and executed under his direction. While his impress was thus stamped upon the public works of Scotland, he was often consulted upon those of England and Ireland; and his ingenious plans of simplifying and adapting, which he had so successfully employed upon one element, were followed by those which were equally fitted for the other. In this way, his suggestion of the new form of a suspension bridge applicable to small spans, by which the necessity for tall piers is avoided, was partially adopted in the bridge over the Thames at Hammersmith. While planning a timber bridge for the Meikle Ferry, he also devised an arch of such simple construction, composed of thin layers of plank bent into the circular form, and stiffened by king-post pieces, on which the level roadway rests, that this form of bridging has come into very general use in the construction of railways.

As an author Mr. Stevenson has not been particularly fertile. He sat down to draw a plan instead of excogitating a theory, and his published work was the erection itself, instead of a volume to show how it might be accomplished. Still, however, he has written sufficiently for one who did so much. Independently of his large work upon the Bell Rock lighthouse, he wrote several articles in the "Encyclopedia Britannica,"and Brewster’s "Edinburgh Encyclopedia," and other scientific journals. In 1817 he published a series of letters in the "Scots Magazine," giving an account of his tour through the Netherlands, and a description of the engineering works connected with the drainage and embankment of Holland. His professional printed reports and contributions are also sufficient to occupy four goodly quarto volumes. Owing, however, to the obstacles under which his early education was impeded, he had not acquired that facility in composition which a commencement in youth is best fitted to impart, so that we question whether, in his great achievement of the Bell Rock, his book or his lighthouse occasioned him most trouble. In 1815 he became a fellow of the Royal Society of Edinburgh; he afterwards joined the Geological Society of London, and the Wernerian and Antiquarian Societies of Scotland.