Marking the rock off Boston Harbour, it is one of the greatest works completed by the lighthouse builders of the United States. It forms the theme of Longfellow’s well-known poem.]
This sensational disaster, after a brief existence of three years, did not augur well for the permanence of a light upon this precarious ledge. The Outer Minot appeared to be determined to continue its plunder of ships, cargoes, and lives, untrammelled. Accordingly, for three years no effort was made to bring about its subjugation.
In 1855 General Barnard, one of the most illustrious engineers which the United States has ever produced, brought forward the plans for a structure which he thought would resist the most formidable attacks of wind and wave. He took Rudyerd’s famous Eddystone tower as his pattern. This was perhaps the strongest design that could be carried out against the sea, having one weak point only--it was built of wood. General Barnard contemplated a similar structure for Minot’s Ledge, but in masonry.
The Lighthouse Board, which had recently been inaugurated to control the lighthouses around the coasts of the country, examined the idea minutely, and submitted the design to the most expert criticism and discussion, but all were so impressed with its outstanding features that they decided to support it whole-heartedly. A minute survey of the rock was prepared, and the plans were straight away perfected for the preparation of the masonry on shore. So carefully was this work carried out, that, with the exception of a few blocks of masonry constituting the foundations, which had to be prepared on the site, and some slight variations in the method of construction, the original ideas were fulfilled.
Work was commenced in 1855, the building operations being placed in the hands of B. S. Alexander, at that time Lieutenant of Engineers, and the successful completion of the work was due in a very great measure to his ability and ingenuity, because the whole undertaking was placed in his hands and he had to overcome difficulties at every turn as they arose.
The builder was handicapped in every way. First there was the brief period in which operations could be carried out upon the site, the working season extending only from April 1 to September 15 in each year. This is not to say that the masons were able to toil upon the rock continuously every day during this interval--far from it. In order to get the foundations laid there were three essentials--a perfectly smooth sea, a dead calm, and low spring-tides. Needless to say, it was on very rare occasions indeed that these three requirements were in harmony. As a matter of fact, they could occur only about six times during every lunar month--three times during full moon, and three at the change. Even then, either the wind or the sea intervened to nullify the benefits arising from the lowest tides. So much so that, although work commenced at daybreak on Sunday, July 1, 1855, only 130 working hours were possible upon the rock before labours ceased for the season in the middle of the following September.