Steam Power is a magazine story.
The Fat Controller tells the engines that the weatherman has forecast snow for the following day and that Thomas must go to the mine and collect an extra delivery of coal. Percy warns his friend to keep an eye out for 'Arry, who is working at the mine.
Sure enough, when Thomas arrives at the mine, 'Arry bustles up and starts boasting about how Diesels are superior to steam engines. He says that Diesel engines do not need to burn dirty old coal and puff steam through funnels. Thomas is glad when the coal is loaded and he races back to the sheds.
A few days later, the Fat Controller comes to see Thomas again. He informs Thomas that he is to go to the mine again because 'Arry has been stuck there for two days with no fuel. Thomas hurries off and soon arrives at the mine with a tanker of fuel for 'Arry, who is shivering and covered in snow. Thomas politely asks if 'Arry would like to warm himself at his fire. 'Arry pretends not to hear.