Archives for posts with tag: structural engineering

What is it about lighthouses that captures the imagination—mine, anyway—and directs it out to sea? Their silent performance of a thankless duty? Their stoic disregard of the extreme marine climate? Their stark but elegant beauty and strong but lean engineering?

Whenever I see one, I immediately start to think about how the beacon might appear to a passing ship or, more appropriately, a boat bound for whatever harbor is nearby. What does the lighthouse look like from a mile or two offshore?

Not much, probably. During the day, details of coastal structures are difficult to make out. A lighthouse may seem immense to someone standing at its base but from afar, even the tallest tower will be dwarfed by the mountains and cliffs that often loom over coastlines.

And at night, all that can be seen is a ray of light.

I can’t recall ever spotting a lighthouse beacon from a boat or ship (truthfully, I’ve spent very little time on water) but I have seen one from afar. A few years ago, we spent a delightful early summer weekend in Bermuda. Our resort was on the southwest coast of the island, facing the North Carolina shore, only a few hundred miles away.

Bermuda is small enough and sufficiently isolated from other places that its night sky is truly dark. Looking out through the sliding glass door of our room early one morning, we detected the motion of a faint beam of light as is it flashed across the horizon.

The source of the light fell well below our view (by several miles, at least), but the sweeping path the ray of light followed was immediately recognizable as that from a lighthouse beacon. It was somehow comforting to see evidence that across the lonely expanse of open ocean lay our home.

Back in the golden days of ship travel, it must have been heartwarming to those returning from a long voyage across the ocean to see a first sign that other people were preparing for the ship’s arrival, that at least one person was waiting up in anticipation.

Nowadays, that comfort is a bit cold. While visiting lighthouses here in Maine (of which there are many, given the state’s craggy shoreline), we have learned that most, if not all, of the facilities are automated. The charming cottages that were once home to lighthouse keepers (and their families, if they were lucky) are now vacant.

Fortunately, there are historical societies and preservation groups such as the American Lighthouse Foundation to tend them and offer tours. And, as we learned at Owl’s Head Lighthouse, the United States Coast Guard still sends someone around to ensure that the lights are in working order so that even if no one is home, someone has left a light on for us.


Last Saturday, Rachel and I made an early spring visit to Stonecrop Gardens (see March 22, 2014). The Open House being celebrated that day focused on their indoor collection, which is extensive, if not encyclopedic; much more than can be described in the average 500-word blog post. In fact, at the end of the last account, having finished our snack (cookies and cocoa) we realized that we were only about halfway through the list of plants on display.

What remained to view (not counting the outdoor areas still covered by snow and ice) were the Alpine House, the End House and the Pit House. Of these, my favorite is the Pit House, and not just for the flowering bulbs and succulents that inhabit it. Architecturally, it is unlike any other greenhouse I have seen.

A long, narrow building, its floor is set into the ground by about two feet; stone steps at each end lead down to its central aisle. The tops of the planting beds along either side are at grade level so all of the soil is essentially subterranean. The gabled glass roof springs from short masonry walls that extend about two feet above grade.

The peak of the roof—this is my favorite detail—is supported by two parallel lines of steel wide flange beams that are aligned with the fronts of the planters, thereby maximizing headroom over the aisle. Structurally, the Pit House is quite elegant (and that’s the nicest thing that I, as a structural engineer, can say about it).

Despite its partial embedment in the earth and glazed roof, the Pit House is not particularly warm inside. Nonetheless, it is cozy, mainly due to its diminutive scale. It feels not unlike a child’s playhouse although clearly, serious work is going on in there.

The beds are literally overflowing with a densely-planted collection of ranunculus, fritillaria, narcissus, primula, cyclamen and helleborus, to name just a few. Although only about a third of the area of the Conservatory, the Pit House contains two-thirds the number of different plants.

We strolled leisurely from one end to the other, enjoying the colorful blossoms that sprang from the garden beds at waist level or trailed along the steel beams over our heads. We left with an infusion of spring spirit and a renewed enthusiasm to get to work in our own garden.