How did Passepartout manage to stop the train?

Passepartout crawled out and under the train and etached the train from the engine.

"Stay, monsieur," cried Passepartout; "I will go."

Mr. Fogg had not time to stop the brave fellow, who, opening a door unperceived by the Indians, succeeded in slipping under the car; and while the struggle continued and the balls whizzed across each other over his head, he made use of his old acrobatic experience, and with amazing agility worked his way under the cars, holding on to the chains, aiding himself by the brakes and edges of the sashes, creeping from one car to another with marvellous skill, and thus gaining the forward end of the train.

There, suspended by one hand between the baggage-car and the tender, with the other he loosened the safety chains; but, owing to the traction, he would never have succeeded in unscrewing the yoking-bar, had not a violent concussion jolted this bar out. The train, now detached from the engine, remained a little behind, whilst the locomotive rushed forward with increased speed.

Carried on by the force already acquired, the train still moved for several minutes; but the brakes were worked and at last they stopped, less than a hundred feet from Kearney station.