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T. D. Judah

T. D. Judah is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand T. D. Judah rather than just read about it. In short: T. D.

T. D. Judah — main illustration
T. D. Judah — illustration

Key takeaways

  • T. D. Judah belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect T. D. Judah to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of T. D. Judah from memory before moving on to harder problems.

Reference excerpt

T. D. Judah was the name of a 4-2-2 steam locomotive owned by the Central Pacific Railroad. It was named in honor of the railroad's first chief engineer, Theodore Dehone Judah, who had championed and surveyed a passable route over the Sierra Nevada for the Transcontinental Railroad.

History and career Like its sister engine, C. P. Huntington, T. D. Judah was originally built by the Cooke Locomotive Works in 1863 for a railroad that was unable to pay for it. Later, the two were seen in the Cooke shops by Collis Huntington and purchased for use on the Central Pacific Railroad (CP), becoming the road's third and fourth locomotives respectively. Two other, larger engines, Gov. Stanford (number 1, built by Norris Locomotive Works) and Pacific (number 2, built by Mason Machine Works) had been purchased earlier. Originally built as a 4-2-4T Forney type, T. D. Judah was a locomotive and tender on one frame. In 1872 the engine was rebuilt as a 4-2-2 with separate tender and may have been given other mechanical upgrades like its sister engine. The rebuild reduced the locomotive's overall weight to 30,000 lb (14,000 kg), with 15,000 lb (6,800 kg) on the drivers. T. D. Judah was sold to the Wellington Colliery Company on Vancouver Island, British Columbia, Canada, where it found service as Wellington Colliery Railway's Queen Anne. It was subsequently scrapped in 1912.

In popular culture In the 1991 film The Little Engine that Could, Tillie and Jebediah are based on this engine but are portrayed as 4-2-2 tank engines.

References Diebert, Timothy S. & Strapac, Joseph A. (1987). Southern Pacific Company Steam Locomotive Conpendium. Shade Tree Books. ISBN 0-930742-12-5. Dunscomb, Guy (1963). A Century of Southern Pacific Steam Locomotives 1862–1962. Guy L. Dunscomb & Son. Yenne, Bill (1985). The History Of The Southern Pacific. Bison Books Corp. ASIN B000ICKVU4.

Illustrations

T. D. Judah illustration

Worked examples

Example 1 — a first encounter with T. D. Judah

Start with the simplest possible case. Write down what T. D. Judah claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to T. D. Judah before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about T. D. Judah ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of T. D. Judah

In research
T. D. Judah appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses T. D. Judah in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
T. D. Judah is common in secondary-school and first-year university syllabi. It links to neighbouring topics 4-2-2 locomotives, 4-2-4T locomotives, Cooke locomotives, so understanding it makes those chapters shorter.
In everyday life
Look for T. D. Judah outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study T. D. Judah in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what T. D. Judah means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain T. D. Judah out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is T. D. Judah in simple terms?

T. D.

Why does T. D. Judah matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study T. D. Judah?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on T. D. Judah.

Tags

  • 4-2-2 locomotives
  • 4-2-4T locomotives
  • Cooke locomotives
  • First transcontinental railroad
  • Railway locomotives introduced in 1863
  • Scrapped locomotives
  • Southern Pacific Railroad locomotives
  • Standard-gauge locomotives of the United States
  • Steam locomotives of the United States

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