David Napier, son of John Napier, was born at Dumbarton on 10th November 1790, and was thus a few months older than his cousin.

At the time of his birth his father, who was the eldest of his family, worked in Dumbarton, but a few years later, in 1802, he removed to premises in Glasgow in the neighbourhood of Jamaica Street.

When he was five years of age David was sent to the public school at Dumbarton, where he received instruction similar to his cousin Robert. Subsequently, on his removal to Glasgow, his education was continued, and he was taught drawing and mathematics by Mr Peter Nicholson, the well-known authority on architecture, who along with John Napier was one of the founders of the Royal Philosophical Society.

Though David never served a regular apprenticeship, he turned his hand to everything, and at the early age of twenty he was taking charge of his father’s business. His father died when he was young, and the care of the foundry fell on him. Among his father’s friends and customers — who were not very regular paymasters—was Mr Henry Bell, known at this time as a house builder. In this capacity he had been in the habit of visiting Napier’s foundry in Howard Street, and when he resolved on his experiment with the Comet he gave Napier the order for the boiler and castings required. David Napier was thus in the very forefront of steam navigation; and, grasping the fact of the future of steam-boats, he erected works at Camlachie Burn, in the east end of Glasgow, for the purpose of making small marine engines, which he supplied to the river steamers then building.

In those early days it was considered impossible to make ship’s machinery capable of withstanding the shock of a heavy sea, and steam-boats did not venture outside the Cumbrae Heads in stormy weather.

Napier was familiar with the works of Bossut on the resistance of fluids; and after making some passages in the Belfast sailing-packets, he came to the conclusion that the full bow then considered necessary was not a form suitable for easy propulsion. He therefore boldly resolved to build a steamer for the Channel trade in conformity with his own ideas. His first step was to make a model proportional to the length, breadth, and depth he contemplated; and having erected a framework on the top of which was a drum for winding up a weight, he began making “tank experiments” in Camlachie burn. He continued fining the bow as long as there was any perceptible increase in speed, taking care to keep the weight of the block the same. Having at length in this manner determined the most suitable form, he handed the model to the builder, with instructions that the vessel was to be constructed in conformity therewith.

This steamer was called the Rob Roy, and despite all predictions of failure, she proved a great success. With her in 1818 he instituted regular steam communication between Greenock and Belfast, and afterwards sold her to the French Government, who, changing her name to Henri Quatre, employed her for years in the Channel trade. He thus established over-sea communication; and the Blue-books of the House of Commons record the fact that the vessels built by David Napier were the first to demonstrate the practicability of navigating the open sea by steamer.

His reputation as a marine engineer brought him many orders, and for the extension of his business he was induced to purchase lands at Lancefield, in the west end of Glasgow, adjoining the Clyde. There he erected improved works, and also made a dock or wet basin; and having no further need of his Camlachie premises, he leased the foundry to his cousin Robert. For many years he was assisted by David Tod and John Macgregor, who acted as his managers, and who subsequently founded the well-known firm of Messrs Tod & Macgregor.

In 1826 he engined the celebrated vessel United Kingdom, the first of the so-called leviathans. She was 160 feet long + 26J feet beam, with engines of 200 N.H.P., and was considered the wonder of her day. People flocked from all quarters to see her, the general public predicting that she would be too unwieldy at sea. She left the Clyde on 29th July 1826, with 150 passengers on board, and made the voyage to Leith round the north of Scotland in sixty-five hours.

David Napier’s brain was of the most fertile character; and in addition to introducing many improvements into steamers, such as surface condensers, steeple engines, feathering paddles, twin screws, &c., he designed a rotary engine, a floating battery, a breech-loading gun, a steam carriage, and many other novelties.

While his ideas were good his work lacked the substantial qualities which distinguished that done by his cousin Robert, and the records of the Court of Session bear witness to numerous litigations in which perforce he was entangled. The solidity of Robert's work more than counterbalanced the brilliant design of that of his cousin, and gradually he came to have preeminence.

In 1835 a disastrous explosion occurred on one of his steamers, the Earl Grey. She was lying at Greenock, and was preparing to try conclusions with the celebrated Clarence, when her boilers burst, killing and injuring many. This accident affected his health, and in the end of the year David leased Lancefield House and works to his cousin and removed to London, where he afterwards engaged in business with his sons. He built some very fast iron steamers for the Margate traffic, which were considered “highly dangerous” boats. One of them, the Eclipse, became known as “Spring-heeled Jack,” and had the distinction of being immortalised in the ‘Ingoldsby Legends'.

A few years later he retired, and his London yard was acquired by Mr Scott Russell in connection with the construction of the Great Eastern.

At the time of the Crimean War he designed a screw vessel which, in his opinion, would prove invulnerable, and yet have offensive powers capable of destroying anything afloat. She was similar to the Monitor which Ericsson subsequently built. The design showed no sides above water; a curved deck two feet thick, covered outside and inside with thick iron plates, was intended to serve the fourfold purpose of giving the vessel greater buoyancy, increasing the internal head-room, repelling shot, and elevating the aperture of the heavy gun with which he proposed to arm her. He offered to supply a breech-loading gun, made of malleable iron, that would fire twice as quickly as any gun in the Navy, and also suggested that such a weapon, with an iron proof casemate, should be mounted on a steam carriage and worked on land. His suggestions, however, did not find favour with the Authorities, who declined his proposal without assigning any reason.

Another of the projects of his later years had reference to the purification of the Clyde. He submitted a plan for removing the sewage of Glasgow to the open sea by barges, and expressed his willingness to subscribe £500 to test it; but his scheme at that time was not considered, though subsequently in effect adopted.

In his younger days he had acquired a large tract of land at the head of the Holy Loch, where he built houses, and made roads on which he employed his steam carriage, which was the first conveyance of the kind to carry passengers for hire. He also purchased a small estate at Glen-shellish, situated near the north end of Loch Eck, where he loved to stay in lonely solitude, thinking out and maturing many of his inspirations of genius.

After his retiral from business he lived chiefly at Worcester, from which place we find him writing to his cousin in 1864.

Worcester, Jan. 11, 1864.

Dear Cousin,— ... I am glad to learn my sister is so much better than she was. The accounts were so alarming I received at one time, that I had a suit of black prepared, all ready for a start for Scotland if the next post had not brought intelligence that she was rather better. The probability now is that she will wear black for me instead. It is of very little consequence who goes first. One just goes a little before the other, and all are soon forgotten.—I am, dear Cousin, yours truly,    David Napier.

Robert Napier, Esq.

I can still eat and drink pretty well, but cannot walk any distance without the fear of falling.

The end came a few years later, and he died in London in 1869, in the eightieth year of his age.

It has been said that, excepting his cousin Robert, no man contributed more to the success of steam navigation than David Napier of Glenshellish.