THE MINOT’S LEDGE LIGHT
Lovers of Longfellow will recall the poet’s song to the lighthouse,
but how many of his admirers know to what beacon these stirring lines
refer? When they were penned the author had in his mind’s eye an
example of the engineer’s handiwork which ranks as one of the finest
sea-rock lights in existence, worthy of comparison with the most famous
of similar structures scattered throughout the waters washing the Old
World.
This is the far-famed Minot’s Ledge light, warning the seafarer making
to and from Boston Bay of the terrible peril which lurks beneath the
waves on the southern side of the entrance to this busy indentation.
“Like the great giant Christopher it stands,” a powerful monument to
engineering genius, dogged perseverance against overwhelming odds, and
a grim, bitter contest lasting five weary years between the implacable
elements and human endeavour. The Minot Ledge is one of those jagged
reefs which thrust themselves far out into the sea, studded with
pinnacles and chisel-like edges, which never, or very seldom, protrude
above the waves. Ship after ship fouled this danger spot, either to be
sunk or to be so badly crippled that it barely could contrive to crawl
to safety.
The prosperity of Boston was threatened by this peril to shipping, and
therefore it is not surprising that a resolution was passed to devise
some ways and means of indicating its presence to those who go down
to the sea in ships. The solution was offered in a skeleton structure
fashioned from iron, which was designed by Captain W. H. Swift, of the
United States Topographical Engineers. He searched the reef through and
through to ascertain the point where the beacon should be placed so as
to prove of the greatest value. This in itself was no simple matter,
inasmuch as Minot’s Ledge is but one of a great area of wicked crags,
which collectively are known as the Cohasset Rocks, and which straggle
over the sea-bed in all directions. After the position had been
reconnoitred thoroughly, and sounding and levels had been taken, the
engineer decided that the most seaward rock of the group, known as the
Outer Minot, would be the most strategical position, and accordingly he
planned to erect his beacon thereon.
It was a daring proposal, because the reef at the point selected only
exposes some 25 feet of its mass above the falling tide, and then the
highest point of the rock scarcely thrusts itself 3½ feet into the air.
It was realized that the periods of working between the tides would
inevitably be very brief, while even then, owing to the open position
of the ridge, a landing would only be possible in very smooth weather,
and the men would have to suffer exposure to the fury of the waves as
they dashed over the ledge.
Captain Swift decided upon a skeleton iron structure, not only because
it would be quicker to erect and would cost less, but because it
would offer the least resistance to the waves, which would be free to
expend their energy among the stilts. The task was taken in hand at
the first favourable opportunity, and, the system lending itself to
rapid construction, marked progress was made every time the workmen
succeeded in getting on the ledge. The lantern and keepers’ quarters
were supported upon nine piles, 60 feet above the rock. The legs were
so disposed that eight described the circumference of a circle, while
the ninth constituted the axis.
This tower was completed in 1848, and for the first time the navigator
making these treacherous waters received a powerful warning to keep
clear of Minot’s Ledge. For three years the beacon survived the
battering of wind and wave, but its welcome beam was last seen on the
night of April 16, 1851. In the spring of that year a gale of terrific
fury beat upon the Massachusetts coast. The wind freshened on April
13; the next day it rose to its full force, and did not abate for
four days. The good people of Boston grew apprehensive concerning the
plight of the two keepers of the lonely Minot’s light, but, however
willing they might have been to have put out to the beacon, they were
absolutely impotent before the ferocity of the elements. Time after
time the light vanished from sight as it was enveloped in an angry
curling mountain of water. On April 17 the doleful tolling of the
lighthouse bell was heard, but the light was never seen again. The
structure had slipped completely from sight, together with its faithful
keepers, swallowed by the hungry Atlantic. Evidently the wail of the
bell was a last plea for assistance, because no doubt the lighthouse
had bowed to the storm and was tottering when the tolling rang out. But
the call brought no help; it was the funeral knell of the guardians of
the beacon. When the sea went down a boat pushed off to the ledge, and
all that was seen were a few bent piles. Captain Swift had done his
work well. The waves could not tear his beacon up by the roots, so had
snapped off the piles like carrots, and had carried away the lantern.
[Illustration: THE MINOT’S LEDGE LIGHT.
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.
[Illustration: TENDER LANDING BUILDING MATERIAL UPON THE TILLAMOOK ROCK.
A derrick has been provided to facilitate these operations, while a
stairway leads from the landing point to the lighthouse.]
On gaining the rock, Lieutenant Alexander decided to make use of
the holes which had been driven into the granitic mass by Captain
Swift to receive the piles of the previous structure. The twisted
and broken pieces of iron were withdrawn and the holes cleaned out.
Simultaneously the upper surface of the rock was pared and trimmed by
the aid of chisels, which was no easy task, because at times the masons
were compelled to manipulate their tools as best they could in two
or three feet of water. This preparation of the rock to receive the
base constituted one of the most notable features of the work. In the
greater number of other outstanding achievements upon sea-rocks the
surface of the latter has been above the waves at lowest spring-tides,
whereas in this case a great part of the foundation work was
continuously submerged.
This preparation of the rock-face necessitated the final trimming and
shaping upon the site of many of the masonry blocks forming the root of
the tower. They could not possibly be prepared ashore to bring about
the tight fit which was imperative. Accordingly, all but the bottom
faces of the blocks were prepared in the depot on the mainland, and
they were then shipped to the ledge for final paring and trimming.
The attachment of the bottom courses to the rock-face was carried
out very ingeniously. Bags of sand were brought on to the rock and
laid around the spot upon which a particular block of stone was to be
laid. The sacks, being filled with sand, were pliable, so that, when
deposited, they adapted themselves to the contour of the ledge, and
prevented the water making its way in under the rampart. The water
within this small dam was then removed, sponges being used in the
final emptying task, so as to suck out the salt sea from the cracks
and crevices, leaving the surface on which the block of stone was to
be laid quite dry. A film of cement was then trowelled upon the rock
surface, and upon this was laid a sheet of muslin. The inclusion of the
muslin was a wise precaution, because while the work was in progress
a wandering wave was liable to curl over the rock, swamping the small
dried space, when, but for the presence of the muslin, the cement
would have been carried away. At the same time the cement was able to
penetrate the meshes of the muslin when the stone was deposited, so as
to grip the surface of the latter and to hold it tightly in position.
Under such abnormal conditions of working the masons had many exciting
moments. No matter how smooth was the sea, several renegade waves
would plunge over the ledge. The masons had to be prepared for these
unwelcome visitors, and precautions had to be introduced to prevent
them being washed off their slender foothold. A substantial iron
staging was erected over the working area on the rock, to facilitate
the handling of the building material. A number of ropes were attached
to this staging, the free ends of which dangled beside the workmen.
These were the life-lines, one being provided for each man. A lookout
was posted, who, when he saw a wave approaching and bent upon sweeping
the rock, gave a shrill signal. Instantly each workman dropped his
tools, clutched his life-line tightly, threw himself prostrate on the
rock, and allowed the wave to pass over him. The situation certainly
was uncomfortable, and the men often toiled in soddened clothes, but
an involuntary bath was preferable to the loss of a life or to broken
limbs.
Work advanced so slowly that during the first two years, which were
devoted to the excavation of the pit and the preparations of the
rock-face, only 287 hours’ work were accomplished. In the third year
this task was completed, and four stones laid in a further 130 hours
21 minutes. By the end of the working season of 1859 twenty-six
courses were finished, so that, while the volume of work fulfilled in
1,102 hours 21 minutes, and spread over five years, certainly was not
imposing, it was remarkable under the circumstances.
The stones for the foundations were sent from shore with the indication
-3’ 5”, -2’ 9”, -1’ 3”, and so on, indicating that these stones were
prepared for positions 3 feet 5 inches, 2 feet 9 inches, and so on,
below zero. And the zero mark was 21 inches below water! Above the zero
mark the stones were prefixed by a “plus” sign.
The shaft is purely conical, and solid except for a central well
extending from the foundations up to the level of the entrance. The
successive courses of stones were secured to one another, and each
stone was attached to its neighbour in the ring by the aid of heavy
iron dogs, so that the lower part of the shaft forms a practically
solid homogenous mass. What are known as continuous “dowels” were
sunk through each course of masonry into the holes in the solid
rock prepared by Captain Swift for his skeleton light, this further
attachment of the mass to the ledge being continued until the twelfth
course was gained. Thus additional security is obtained by anchoring
the tower firmly to the reef.
The solid portion of the building is 40 feet in height from the level
of the first complete ring of stones, and the tower is 80 feet high
to the lantern gallery. The over-all height to the top of the lantern
cupola is 102¾ feet, while the focal plane is 84½ feet above mean
high-water. The first stone was laid on July 9, 1857, while the masons
completed their duties on June 29, 1860, so that five years were
occupied upon the work. In erection 3,514 tons of rough and 2,367 tons
of hammered stone, in addition to 1,079 numbered stones, were used, and
the total cost, including the light-keepers’ houses on the mainland,
was £60,000, or $300,000, so that it ranks among the more costly lights
which have been provided for the seafarer’s benefit.
On November 15, 1860, nine and a half years after the destruction of
the first beacon, the light was once more thrown from Minot’s Ledge for
the benefit of passing ships. The light is of the second order, visible
fourteen and three-quarter miles out to sea, and is of the flashing
type, signalling “143” every thirty seconds thus--one flash followed by
three seconds’ darkness, four flashes with three seconds’ eclipse, and
three flashes with an interval of fifteen seconds’ darkness.
The tower has been subjected to repeated prodigious assaults, the
north-east gales in particular thundering upon this reef with
tremendous fury, but it has withstood all attacks with complete
success.