The Long Boiler locomotive was the object of a patent by Robert Stephenson

Robert Stephenson

Robert Stephenson FRS was an English civil engineer. He was the only son of George Stephenson, the famed locomotive builder and railway engineer; many of the achievements popularly credited to his father were actually the joint efforts of father and son.-Early life :He was born on the 16th of...

 and the name became synonymous with the pattern.

History

It is generally perceived that it arose out of attempts to match the power of broad gauge

Broad gauge

Broad-gauge railways use a track gauge greater than the standard gauge of .- List :For list see: List of broad gauges, by gauge and country- History :...

 locomotives within the limitations of the loading gauge of Stephenson railways. However, the patent originally arose from a problem which became apparent as trains travelled longer distances, specifically on the North Midland Railway

North Midland Railway

The North Midland Railway was a British railway company, which opened its line from Derby to Rotherham and Leeds in 1840.At Derby it connected with the Birmingham and Derby Junction Railway and the Midland Counties Railway at what became known as the Tri Junct Station...

 in England around 1841, where fire tubes and smokeboxes were becoming destroyed by the heat.

Experiments at the North Midland's Derby Works

Derby Works

The Midland Railway Locomotive Works, known locally as "the loco" comprised a number of British manufacturing facilities in Derby building locomotives and, initially, rolling stock in Derby, UK.-Early days:...

 showed temperatures as high as 773 degrees Fahrenheit, determined by placing a small cup of zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 within the smokebox beneath the chimney. Stephenson extended the boiler, and hence the firetubes, from the usual nine feet to thirteen or fourteen feet. Placing tin

Tin

Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

 in the firebox, he found that it just began to melt, indicating a temperature of 442 degrees.

Having tested the design on the North Midland line between Derby

Derby

Derby , is a city and unitary authority in the East Midlands region of England. It lies upon the banks of the River Derwent and is located in the south of the ceremonial county of Derbyshire. In the 2001 census, the population of the city was 233,700, whilst that of the Derby Urban Area was 229,407...

 and Leeds

Leeds

Leeds is a city and metropolitan borough in West Yorkshire, England. In 2001 Leeds' main urban subdivision had a population of 443,247, while the entire city has a population of 798,800 , making it the 30th-most populous city in the European Union.Leeds is the cultural, financial and commercial...

, Stephenson took out a patent in 1842 for what he referred to as a "Long Boiler" engine. To protect his patent, he realised that he should not specify an exact length.

Meanwhile, the prevailing view was that the centre of gravity should be as low as possible, which limited the size of the driving wheels, and incidentally precluded the use of inside cylinders.

The initial locomotives were of 2-2-2

2-2-2

Under the Whyte notation for the classification of steam locomotives, 2-2-2 represents the wheel arrangement of two leading wheels on one axle two powered driving wheels on one axle, and two trailing wheels on one axle. The wheel arrangement both provided more stability and enabled a larger firebox...

 wheel arrangement to accommodate the extra length. However, with the outside cylinders, the engines were extremely unsteady, swaying from side to side. This led Stevenson to bring the rear wheels forward in the 4-2-0

4-2-0

Under the Whyte notation for the classification of steam locomotives, 4-2-0 represents the wheel arrangement of four leading wheels on two axles, two powered and coupled driving wheels on one axle, and no trailing wheels...

 formation, with the cylinders between the leading wheels. Such an engine was the "Great A" which took part in the Gauge Trials. This however, left the firebox behind the wheels and was therefore limited in size and weight. Moreover, the long rigid chassis made bends difficult to negotiate and damaged the track. The classical long-boiler locomotive, then, was powerful but slow. It was ideal for goods trains, one example surviving as the North Eastern Railways Class 1001

NER 1001 Class

The North Eastern Railway 1001 Class was a class of "long-boiler" 0-6-0 steam locomotive designed in Britain.-Technical data:A NER 1001 class locomotive weighed about 35 tons, with a wheelbase of and diameter driven wheels. Its diameter boiler produced over 7 tons of tractive effort at 140...

.

The opposite point of view was taken by John Gray

John Gray (locomotive engineer)

John Gray was an early steam locomotive engineer who introduced several innovations in locomotive design during the 1830s and 1840s.-Career:John Gray's origins are unknown but he appears to have originated from Newcastle...

, who designed a number of engines for the London and Brighton Railway

London and Brighton Railway

The London and Brighton Railway was a railway company in England which was incorporated in 1837 and survived until 1846. Its railway runs from a junction with the London & Croydon Railway at Norwood - which gives it access from London Bridge, just south of the River Thames in central London...

. His engines were the inspiration for David Joy

David Joy

David Frederick Joy was a former professional footballer, who played for Huddersfield Town and York City.-References:*99 Years & Counting - Stats & Stories - Huddersfield Town History...

 in his design for the Jenny Lind locomotive

Jenny Lind locomotive

The Jenny Lind locomotive was the first of a class of ten steam locomotives built in 1847 for the London Brighton and South Coast Railway by E. B. Wilson and Company of Leeds, named after Jenny Lind who was a famous opera singer of the period...

, which compensated for the size of its boiler by greater efficiency and a pressure of some 120 psi.

The long boiler design, on the other hand, was taken to its extreme by the Crampton locomotive

Crampton locomotive

A Crampton locomotive is a type of steam locomotive designed by Thomas Russell Crampton and built by various firms from 1846. The main British builders were Tulk and Ley and Robert Stephenson and Company....

which utilised a larger driving wheel by placing it behind the firebox.