Patents and more locomotives
In the year that he developed the miner's safety lamp
— 1815 — Stephenson was also continuing with his work as enginewright to the Grand Allies' various collieries, and the family continued to live at West Moor. Never one for idleness, he also found time to patent his plans for improving steam-powered locomotion, and construct colliery railways as well as devote attention to his son Robert Stephenson
's (1803-59) education.
The beginning of the year found him still wrestling with the challenge of propelling steam locomotives smoothly and more quietly along rails. Blücher
(1814), his first locomotive, had spur gears that proved awkward at transmitting power equally to the wheels. As Richard Trevithick
(1771-1833) had attempted earlier, Stephenson decided to use direct coupling and get rid of the cog wheel gearing.
On 28th February 1815, with Killingworth Colliery's manager Ralph Dodds (1792-1874), he took out Patent No. 3887 Construction of locomotive-engines for locomotive coupling rods and crank pins. Putting the patent into practice involved moving the two vertical cylinders apart inside the boiler, placing them above the front wheels, and coupling connecting rods to crank pins on the wheels with a chain drive between front and back axles. The patent also covered the use of cranked axles with one internal coupling rod between frames — a more elegant solution but beyond the capabilities of the Killingworth blacksmiths.
Dodds' assistant and Stephenson's friend, Nicholas Wood (1795-1865), noted the improvements and recorded that "An engine of this [new] construction was tried upon the Killingworth Rail-road, on March 6th, 1815, and found to work remarkably well". The engine also featured slide valves for regulating the steam, for which Wood developed the valve actuating system. However, the chain drive tended to stretch with use, eventually causing irregular locomotion. It was later superseded by horizontal external coupling rods to the wheels.
After work Stephenson spent time with Robert, who reported on his studies or read from the library books. Father and son also collaborated on practical projects, such as the design of a sundial. Robert, still only 13 years old, carried out the computations, later remarking, "Many a sore head I had while making the calculations to adapt the dial to the latitude of Killingworth ... then my father got a stone, and we hewed, and carved, and polished it, until we made a very respectable dial of it". The sundial was erected on 11th August 1816 above the door of the West Moor cottage, where it remains to this day. The house is now called Dial Cottage in its honour.
Robert's sundial drawing was presented to William Losh (1770-1861), who had taken Stephenson's side in the safety lamp argument. Losh was a wealthy industrialist with colliery interests and works near Newcastle for the manufacture of chemicals and iron. He and Stephenson collaborated on the development of more-resilient cast iron rails.
On 30th September 1816, the pair were granted Patent No. 4067 Construction of railways and frameways for facilitating the conveyance of carriages, goods, and materials along the said ways and frameways, by improvements in the construction of the machine, carriages, carriage wheels, railways and frameways employed for that purpose.
The patented improvements included the 'steam spring' (see below), wheels of malleable rather than cast iron, profiled rail chairs and half-lap jointed cast iron rails. The latter were laid along all of Killingworth Colliery's wagonway.
The steam spring was an early form of pneumatic suspension. Vertical cylinder and piston arrangements attached to the axles, with their upper ends open to the boiler, carried most of the engine's weight on a cushion of steam provided by the pressure in the boiler. Stephenson used this system until sufficiently robust laminated springs were available. He would produce 16 more locomotives in the Killingworth workshops, plus a six-wheeled locomotive for the Kilmarnock & Troon Railway
— the first railway engine in Scotland.
In 1819, while still employed by the Grand Allies, Stephenson was appointed engineer to the proposed Hetton Colliery Railway
in County Durham, with his brother Robert (1788-1837) as resident engineer. The 12.6km line was the first railway not to use animal power, using instead steam locomotives and rope haulage from stationery steam engines. That same year, his son Robert left John Bruce's academy in Newcastle to become Wood's apprentice at Killingworth.
As for his private life, Stephenson had been on his own long enough. He resumed courting his former sweetheart Elizabeth 'Betty' Hindmarsh (1777-1845), who had remained single. On 29th March 1820, they married at St Michael's church at Newburn, Northumberland. He was 38 years old and Elizabeth 43. Like his sister Eleanor, she was a Methodist, and she was described as "homely, good and kind". She became a loving stepmother to Robert. On 19th November that year, his brother John Stephenson (1789-1831) married Hannah Forster (1800-62) at St John's church in Newcastle.
Now financially secure, Stephenson embarked on his first independent business speculation. In a deed of partnership signed on 5th December 1820, he and colliery owner Thomas Mason each contributed £700 for a 21-year lease on Willowbridge Colliery near Bedlington, County Durham. He would continue to invest in the northern mining industry as his career progressed.
In 1820-23, the largest of Stephenson's steam pumping engines was constructed, for Losh Wilson & Bell. It was installed in the Tyne Main Colliery at Friar's Goose, Gateshead, and operational in July 1823. Its 1.84m diameter cylinder worked a 2.74m stroke, and it was capable of raising almost 90 litres of water per second from a 100m deep shaft with three sets of pumps.
On 21st March 1822, he obtained a patent (No. 4662) for Steam engines. Then, on 18th November 1822, the Hetton Colliery Railway opened. With some upgrading, the line would remain in regular use right up until 1950, closing on 9th September 1959.
It was becoming clear that transporting bulk goods by rail was a commercial proposition, and Stephenson saw opportunities to provide both the tracks and the locomotives. Moving coal from the northern collieries to the coast for shipment to London and elsewhere led to the identification of a major route between Darlington in County Durham, and Stockton on Tees. Though a canal was initially suggested, the railway would win out.
Indeed, the development of nothing less than a national rail network was about to begin. Steam locomotives would carry people and freight across the country, at unprecedented speeds. It was time for Stephenson to venture away from the collieries and take up the challenge of long-distance railway design, ably assisted by his son. Their engineering alliance started with the now-famous Stockton & Darlington Railway
— the world's first permanent public steam-powered railway.
engraving by W Holl after a portrait by John Lucas, published 1862 by John Murray, Albemarle Street, London