Tom Thumb (locomotive)
Tom Thumb was the first American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

-built steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 used on a common-carrier railroad. Designed and built by Peter Cooper
Peter Cooper
Peter Cooper was an American industrialist, inventor, philanthropist, and candidate for President of the United States...

 in 1830, it was designed to convince owners of the newly formed Baltimore and Ohio Railroad
Baltimore and Ohio Railroad
The Baltimore and Ohio Railroad was one of the oldest railroads in the United States and the first common carrier railroad. It came into being mostly because the city of Baltimore wanted to compete with the newly constructed Erie Canal and another canal being proposed by Pennsylvania, which...

 to use steam engines. It is especially remembered as a participant in an impromptu race with a horse-drawn car; the "Tom Thumb" led the race until a belt slipped off a pulley and the engine lost power. The demonstration was successful, however, and in the next year the railroad, committed to the use of steam locomotion, held trials for a working engine.

Design and construction

Tom Thumb was designed by Peter Cooper
Peter Cooper
Peter Cooper was an American industrialist, inventor, philanthropist, and candidate for President of the United States...

 as a four-wheel locomotive with a vertical boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

 and vertically mounted cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...

s that drove the wheels on one of the axles. The "design" was characterized by a host of improvisations. The boiler tubes were made from rifle barrels and a blower was mounted in the stack, driven by a belt to the powered axle. Cooper's interest in the railroad was by way of substantial real estate investment in what is now the Canton neighborhood of Baltimore; success for the railroad was expected to increase the value of his holdings.

Construction was carried out in the machine shop of George W. Johnson, where then 18 year old James Millholland
James Millholland
James Millholland , railway master mechanic, is particularly well known for his invention of many railway mechanisms. His association with the Philadelphia and Reading Railroad Company as master machinist spanned fifty years in the early development of the American railroad...

 was apprenticed. Millholland would later become a prominent locomotive designer in his own right.

Testing was performed on the company's track
Rail tracks
The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, sleepers and ballast , plus the underlying subgrade...

 between Baltimore and Ellicott Mills (now Ellicott City, Maryland
Ellicott City, Maryland
Ellicott City is an unincorporated community and census-designated place in Howard County, Maryland, United States. It is part of the Baltimore-Washington Metropolitan Area. The population was 65,834 at the 2010 census. It is the county seat of Howard County...

). Two tracks had been constructed, and on August 28, 1830 the driver of a passing horse-drawn car bearing passengers challenged the locomotive to a race. The challenge accepted, the Tom Thumb was easily able to pull away from the horse until the belt slipped off the blower pulley and/or a popoff valve was broken or was active. Without the blower, the boiler did not draw adequately and the locomotive lost power, allowing the horse to pass and win the race. Nonetheless, it was realized that the locomotive offered superior performance.

The Tom Thumb was not intended for revenue service, and was not preserved, though Cooper and others associated with the railroad's early days left descriptions which enabled the general dimensions and appearance to be worked out. In 1892, a wooden model was constructed by Major Pangborn (who also had models made of many other early locomotives), and when a replica was constructed in 1926 for the "Fair of the Iron Horse", the builders followed Pangborn's model. The replica therefore differed considerably from the original, being somewhat larger and heavier, and considerably taller (note that the dimensions given above are those of the replica). Also, instead of the blower in the stack, a much larger blower was mounted on the platform to provide a forced draft, and the support frame of the cylinder and guides was considerably different. The replica remains at the Baltimore and Ohio Railroad Museum.
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