The Locomotive is the most unusual recipe in Thomas's 1862 guide by modern standards — a hot wine cocktail enriched with egg yolk that defies clean categorization. It is not quite a mulled wine (too many modifiers, egg yolk), not quite a flip (wine base rather than spirit), and not quite a toddy (no water, too complex). Thomas simply listed it among his hot drinks and gave it a name that conjured the most powerful machine of his era.

In 1862, central heating was rare outside of the very wealthy. American winters were managed with fireplaces, wood stoves, heavy clothing, and warming drinks. Thomas's hot drinks chapter is substantial — the Tom and Jerry, the Blue Blazer, the Mulled Wine, the Hot Toddy, and the Locomotive represent an understanding that hot cocktails were a genuine utility, not a novelty. The choice to heat wine with honey and egg rather than simply with spices and sugar is a recipe decision that connects American bar practice to the much older European tradition of posset and caudle — medieval warm wine or ale drinks enriched with egg and sweetened with honey that had been winter staples since the 14th century.

The drink's name is an advertisement of vigour. Locomotives in the 1860s were the fastest, most powerful machines human civilization had yet produced. They represented industrial ambition and continental conquest — the transcontinental railroad was under construction as Thomas wrote. A cocktail named after one promised the drinker something stimulating and powerful, a useful marketing claim for a warming egg-wine drink.

The Locomotive has not been seriously revived in the modern craft period. Its combination of hot wine and egg yolk is too unusual for standard menus, and its preparation requires technique (careful tempering) that is not suited to bar service at volume. It remains a home bartender's historical curiosity — extraordinary when made well.