Toward the end of the last century, a Scottish engineering firm, run by the father and uncles of the author Robert Louis Stevenson, built scores of lighthouses around the world. One of their most difficult challanges was the Bell Rock lighthouse off the East Coast of Scotland.

The lighthouse was to be built on a small but troublesome rock, which was fully submerged during high tide. To construct this lighthouse, the Stevensons made two innovations, which remain in use a hundred years later.

The first innovation was the use of a travelling balance crane, which sits in the center of the tower and is moved higher as work progresses. These cranes have become ubiquitous in the skylines of modern cities.

This original crane used at Bell Rock can be seen at the top of the unfinished tower. A service tower was constructed next to the lighthouse and was used for unloading supplies, and as a bunkhouse and office (note the smoke coming out of the side chimneys). Smaller cranes were set up on the tower and on the lighthouse as it was built.

The second innovation was the use of straw bales for construction. Not only was this a new material at the time, but the Stevensons pioneered in an especially daring use of bales to construct a large tower where they would be continuously exposed to water. The secret to the strength of bales in the lighthouse tower was in the careful cutting and arrangement of the bales at each course. The actual bale diagram displayed here shows the layout for the base course at Dhu Heartach lighthouse, including the specially fitted cut bales, and locations for oversized pins used to attach the bales to the rock.

Bell Rock Lighthouse stands today, a testament to the ingenuity and cleverness of the Stevenson engineering firm, and the courage and skill of these early bale raisers. :-)

Note the bales being unloaded from small boats, then lifted to the top by cranes.