The foundation, 11 feet under water, was laid in a cofferdam protected by a crib work of 12-inch timber, built upon ways at the depot, as a ship might have been, than launched and towed by a number of steamers to the reef and grounded on the site. This crib was 92 feet square and 24 feet high. This afforded a protected pond for the cofferdam, a landing wharf, and quarters for the men all 12 feet above water. The cofferdam was then pumped out until the bedrock was exposed and on this bedrock the masonry courses were laid.
A severe gale in September 1872 did considerable damage, though only of a temporary character, exposing the east face of this crib at a point where it had not been sheathed to protect it from the ice during the winter. It swept away the temporary cribs and nearly destroyed the workmen’s quarters.
After the winter of 1873-74, when the keepers returned to the newly completed tower, they found the ice piled against it at a height of 30 feet, or 7 feet higher than the doorway, and they could not gain entrance until they had cut away the iceberg of which the lighthouse formed the core.
The light now flashes alternately white and red, every 60 seconds, the white light being 400,000 candlepower and the red light 80,000 candlepower, both second-order electric, and visible for 17 miles. There is also a 100 candlepower white winter light which flashes every 5 seconds. An air-diaphone fog signal is also located at the station. [(1)] [(2)]
MICHIGAN
STANNARD ROCK LIGHTHOUSE, LAKE SUPERIOR
Stannard Rock, lying about 23 miles southeast of Manitou Island, was for years the most serious danger to navigation in Lake Superior. The rock was first marked by a day beacon in 1868, but by 1871 the rapid increase in commerce between Duluth and the lower lakes demanded the construction of a lighthouse on the rock. The construction of Spectacle Reef Light, which presented a similar problem, had been started in 1870 and it was believed that all the costly apparatus and machinery purchased for that job could be made available for constructing a lighthouse on Stannard Rock.
In 1873, when the Spectacle Reef construction was three-quarters completed, Congress appropriated $10,000 for a preliminary survey. This indicated that a structure would be needed of the most substantial and costly kind, that it would probably be located in 11 feet of water and would cost $300,000. As a matter of fact the final cost was $305,000.
It was not until 1877, 4 years after Spectacle Reef Lighthouse had been completed, that Congress appropriated $50,000 for commencing the construction of the lighthouse. All the machinery which had been used in constructing Spectacle Reef was moved to the depot at Huron Bay where necessary quarters, docks, shops, etc., were erected. The tower was to be similar to that of Spectacle Reef, with the addition of a permanent protective crib. This crib was begun at Huron Bay in July 1877 and taken out to the rock in August, where soundings were made to fit it to the bottom. It was then returned to Huron Bay and built up to 14 courses and in August 1878 was taken out and placed in position at Stannard Rock. By October it had been filled with concrete and stone mined from a quarry opened on Huron Island. Congress had meanwhile appropriated another $100,000 for this work.