Atlas used to work on the Mid Sodor Railway as a mine engine. He is in charge of a lot of the goods trains on the railway. Atlas lived in the sheds with Duke, Stuart, Falcon and for a short period of time, Andreas and Stanley.
Following the closure of the Mid Sodor Railway, Atlas was sold to a zinc mine near Cregwir where he was painted blue and given a cowcatcher and sideplates. From there, he ran the tram-line to Harwick working next to the tugboats Ten Cents and Drollan. This was until 1953 when he was "returned to where he came from" following closure of the mines.
It was revealed in Storm Damage that he returned to the Mid Sodor area to replace an old boiler in the flour mill. Here he became known to the Arlesdale engines simply as 'Old Mill' the boiler engine assumed to have been there since the beginning. In 2011 however after a fierce storm on August 17th the mill building endured heavy damage, causing much concern amongst the engines when it was revealed that they may close as a result. Blister 1 however was able to figure out Atlas' true identity after 'Old Mill' mentioning his funnel. With the help of Charlie Hatt the Skarloey Railway purchased Atlas to become their new no. 10 and new maintenance engine.
Atlas is a cab-less Jouef Decauville 0-4-0PT loco that was built in 1899.