Those ponies are fortunate to be able to walk in the fresh air unlike the mine pit ponies that would have spent their day hundreds of feet underground only coming up to the open air for a couple of weeks each year.  This is the view at Prestongrange from near the top of the Beam Engine with part of the enormous beam just visible. It was brought from Cornwall in 1874 in order to pump 4.5 million litres of water a day up from the 420ft (128m) deep coal seam which ran under the sea nearby so allowing coal mining operations to take place.  Fortunately in its 80 years of operation it broke down only twice in its eighty years of operation.
Until about forty years ago this was a very busy industrial area having been started by the monks of Newbattle Abbey for coal mining over eight hundred years ago.  Now very little remains apart from a few buildings including the extensive brickworks, rusting machinery and trucks while nature is taking over.  Yet despite this, there is still much to be seen for anyone interested in industrial archaeology at Prestongrange.