THE LAMP-POSTS OF THE GREAT LAKES OF NORTH AMERICA
On the North American continent the efficient lighting of the coasts
washed by two salt oceans is only one, although the most important,
concern of the United States and Canadian Governments. In addition each
has a long stretch of rugged, tortuous shore hemming in those capacious
depressions draining a vast tract of country, and known generally as
the Great Lakes. These unsalted seas are rightly named, seeing that
they constitute the largest sheets of fresh water on the inhabited
globe.
The responsibility of safeguarding the navigator as he makes his way
across these wastes is shared equally by the two countries which they
divide, with one exception. This is Lake Michigan, which lies entirely
within the United States. The narrow necks of water which link these
lakes into one long chain likewise are lighted by the two nations.
For some years the Lower Detroit River, connecting Lakes Erie and St.
Clair, was maintained for the most part by the United States, but
the practice was not satisfactory; so, as the result of a conference
between the two Governments, Canada assumed charge of the aids in
certain specified portions of the navigable channel lying entirely in
Canadian waters. The result of this new arrangement has been the better
patrolling of the waterway.
The water-borne commerce on these lakes, although possible for only
half the year, is tremendous, while navigation is extremely difficult
and beset with innumerable dangers.[B] The different means whereby a
ship is handled and maintained on its course upon the salt-water ocean
are not completely applicable in this case. The greater number of the
boats are freighters and engaged in the transport of ore, which, from
its metallic character, is apt to disturb the compass, rendering it
somewhat unreliable. Nor is the lead of much avail in thick weather,
as the lake-bed varies suddenly from comparative shallowness to great
depths. Navigation on these lakes has been likened to coastal traffic,
only with land on both sides of the mariner, and the intervals when
the ship is out of sight of the shoreline are comparatively brief.
Accordingly, the captain picks his way rather by the aid of landmarks,
and the vessels are fitted with a bowsprit, to give the master a point
whereby to judge his direction. But landmarks, however conspicuous and
trustworthy they may be by day and in clear weather, are useless at
night and in fog, to which latter visitation, by the way, these waters
are extremely susceptible.
[B] For a full description of the marine traffic on the Great
Lakes, see “The Steamship Conquest of the World,” chapter
ix., p. 119.
Steamship traffic cannot be carried on with financial success by
daylight and in fair weather only, so it became necessary to distribute
beacons around the indented shores. This procedure was rendered
additionally necessary owing to the formidable character of many of the
dangers besetting navigation, in the form of shoals, projecting ridges,
and submerged reefs, quite as terrifying to the master of a fresh-water
ship as similar dangers on an ocean-swept coast.
At the same time, however, one would not expect to find examples of
lighthouse engineering comparable with the great sea-rock lights
rearing above the ocean, such as the Minot’s Ledge, Dhu-Heartach, or
Bishop’s Rock. On the other hand, the uninitiated might conclude that
buoys and small lights, such as indicate the entrance to harbours,
would fulfil requirements. So they would but for two or three adverse
factors. These lakes are ravaged at times by storms of great violence,
which burst with startling suddenness. Fogs also are of frequent
occurrence, especially in the spring and autumn, often descending
and lifting instantly like a thick blanket of cloud. But the most
implacable enemy is the ice. The engineer can design a tower which will
withstand the most savage onslaughts of wind and wave with comparative
ease, at, relatively speaking, little expense; but the ice introduces
another factor which scarcely can be calculated. The whole of these
lakes are frozen over during the winter to such a thickness as to defy
all efforts to cut a channel, becoming, in fact, as solid as terra
firma.
[Illustration:
_By permission of the Lighthouse Literature Mission._
A LIGHTHOUSE ON THE GREAT LAKES IN THE GRIP OF WINTER.
This tower marks the Racine Reef in 20 feet of water near the entrance
to Racine Harbour on the west coast of Lake Michigan.]
In the spring this armour cracks and breaks up like glass shattered
with a hammer. It then becomes the sport of the currents, which in
many places sweep and swirl with enormous force round the headlands
and spits projecting into the lake. This action sets the ice moving
in stately majesty, but crushing everything that rears in its way, or
piling and breaking against the obstruction. Ice-shoves, ice-jams,
and ice-runs, are the three forces against which the engineer has to
contend, and at places his efforts are so puny as to be useless. The
ice, if it collects across one of the outlets so as to form a massive
dam reaching to the lake-bed, immediately causes the level of the
lake to rise; and when at last the barrage breaks, then the water is
released in a mad rush.
Lighthouse building on the Great Lakes demands the highest skill,
incalculable ingenuity, and the soundest of design and workmanship.
Consequently, some of the guardian lights distributed around these
shores, such as Spectacle Reef, the Rock of Ages, Colchester, and Red
Rock lighthouses, are striking evidences of the engineer’s handiwork.
Of course, where the land presses in on either hand, transforming
the waterway into a kind of canal, or where the shore is free from
submerged obstructions, the type of lighthouse on either shore follows
the wooden frame dwelling with a low tower, as it is completely
adequate for the purpose.
The one erection, however, which commands the greatest attention is
the Spectacle Reef light, which has been called the Eddystone, or
Minot’s Ledge, of the Lakes. In its way it was quite as bold an
undertaking as either of these far-famed works, and in some respects
was far more difficult to carry out, although the builder was spared
the capriciousness and extreme restlessness of tidal waters. Spectacle
Reef lighthouse rears its tapering head from a particularly dangerous
reef in an awkward corner of Lake Huron, where commences the Strait of
Mackinac, leading to Lake Michigan. The spot is dangerous, because it
is covered by about 7 feet of water; awkward, because it occurs about
ten and a half miles off the nearest land, which is Bois Blanc Island.
The reef in reality comprises two shoals, which lie in such relation
to one another as to suggest a pair of spectacles--hence the name. As
it is exposed to 170 miles of open sea on one side, when these waters
are roused the rollers hammer on the reef with terrible violence, while
at times the currents skirl by at a velocity of two or three miles per
hour, and the ice in its movement grinds, piles, and grates itself upon
the reef in impotent fury. When this ice is forced forward with the
push exerted by the currents, the pressure is tremendous and the force
wellnigh irresistible.
When the lighthouse was projected, it was realized that it would have
to be of massive proportions and provided with adequate measures to
protect it from the assault and battering of the ice. The task was
undertaken by General O. M. Poe, who was engineer-in-chief to General
Sherman on his historic march to the sea. This engineer decided to
take the Minot’s Ledge monolithic structure as his model, seeing
that the latter had withstood the savage onslaughts of the Atlantic.
Fortunately, the foundations were of an excellent character, the reef
being formed of hard limestone.
[Illustration:
_By courtesy of Lieut.-Col. W. P. Anderson._
BUILDING THE BARRE À BOULARD LIGHT IN THE RIVER ST. LAWRENCE.
Owing to the severity of the ice piling in this waterway, the
structures have to be provided with massive foundations.]
The engineer selected as the site for the tower a point where the
ridge is submerged by 11 feet of water. Seeing that the base was to be
laid under water, obviously it seemed to be an operation for divers;
but General Poe prepared a superior means of getting the subaqueous
foundations laid. He built a cofferdam around the site, and, as the
work would have to be protected from the winter ice, he built another
cofferdam, entirely for protective purposes, outside the former. The
nearest point on the mainland where he could establish a depot was
Scammon’s Harbour, some sixteen miles away, and here everything in
connection with the work was prepared and shipped to the site ready for
placing in position.
The protective work comprised a wooden pier, built up of timbers 12
inches square, 24 feet in height. This structure was divided into a
series of vertical compartments on all four sides, leaving a clear
internal space 48 feet square. The outer compartments or pockets were
filled with stone, to secure solidity and stability. Landing facilities
were provided on this pier, together with quarters for the men engaged
in the construction work.
In the inner space, containing 48 square feet of still water, the
cofferdam, in which the subaqueous work was to be carried out, was
lowered. This structure was cylindrical in form. It was built up
of staves, banded with heavy hoops of iron, so that in reality it
resembled a huge barrel 36 feet across. It was fashioned at the site,
being built while suspended directly over the spot on which it was to
be lowered. When the tub was finished, loosely twisted oakum, 1½ inches
thick, was nailed all round the lower edge, while a flap of heavy
canvas was secured to the outside bottom rim in such a way as to leave
36 inches dangling free. The exact circular shape of the cofferdam was
insured by liberal cross-bracing from a central vertical post, which
constituted the axis of the barrel, corresponding to the vertical axis
of the tower. While this work was in progress, the face of the rock
was cleared of loose boulders, and then the cofferdam was lowered
bodily with extreme care, so that it descended with unerring accuracy
perpendicularly into the water, to come to rest over the desired spot.
As the surface of the reef was very uneven, the cofferdam stopped when
it reached the highest projection under its edge. Then each stave of
the barrel was driven downwards until it came to rest upon the sea-bed,
and, as the oakum rope was forced down likewise, this served to act
as caulking. The outer flap of canvas, when the cofferdam was driven
right home, spread out on all sides, and lay upon the surface of the
reef.
Pumps capable of discharging 5,000 gallons per minute then were set
to work, removing the water from within the cofferdam. The oakum
rope seal prevented the water regaining the internal space under the
bottom edge of the tub, while the canvas assisted in securing absolute
water-tightness, because the outer water-pressure forced it into all
the nooks and crevices.
By these means the workmen were given an absolutely dry space in which
to carry out their erecting work. The face of the reef was cleaned
and levelled off, and the first layer of stones was laid. These were
first fitted temporarily upon a false platform on shore, so that when
they reached the site they could be set at once without finicking. The
bottom layer is 32 feet in diameter, and the tower is solid to a height
of 34 feet above the rock. The stones are each 2 feet in thickness,
and are secured to one another on all sides with wrought-iron bolts,
24 inches long by 2½ inches in diameter; while the tower is anchored
to the rock by cement and bolts 3 feet long, driven through the bottom
course into the real rock beneath, entering the latter to a depth of 21
inches. Liquid cement was driven into the holes so as to fill up all
the remaining interstices, and this now has become as hard as the stone
itself.
The exterior of the tower is the frustum of a cone, and at 80 feet
above the base is 18 feet in diameter. The total height of the masonry
is 93 feet, and the focal plane is brought 97¼ feet above the rock,
or 86¼ feet above the water-level. The tower is provided with five
rooms, each 14 feet in diameter, while the entrance is 23 feet above
the water. The undertaking was commenced in May, 1870, and the light
was shown first in June, 1874. As work had been confined to the summer
months, and a fortnight every spring was devoted to preparations, as
well as an equal period in the autumn to making all fast to withstand
the rigours of winter, the total working period was only some twenty
months.
[Illustration:
_By courtesy of Lieut.-Col. W. P. Anderson._
COLCHESTER REEF LIGHTHOUSE, LAKE ERIE.
An isolated station maintained by the Canadian Government. It is a
fixed light, visible throughout a circle of 16 miles radius.]
The protection against the ice has proved its value completely. The
ice as it moves becomes crushed against the defence, and then has
its advance impeded by the shoal upon which it grinds and packs, to
form in itself a barrier and ice-breaker against other approaching
ice-fields. This structure was soon submitted to a stern test to prove
its efficacy. In the spring of 1875, when the keepers returned to
the lighthouse--the light, in common with all other beacons guarding
the Great Lakes, is shut down during the winter, when navigation is
closed--they found the tower unapproachable. The ice-shove had jammed,
packed, and been frozen into a solid berg to a height of 30 feet, of
which the tower itself formed the core. The doorway was buried to a
depth of 7 feet, and the keepers had to carve their way with pickaxes
to the entrance.
Owing to the success of the design for the Spectacle Reef lighthouse,
which ranks as a striking engineering achievement, it was adopted for
the Stannard’s Rock tower. This ledge rises from the water 28 feet
from shore, and the plant and tackle which were employed in connection
with the first-named structure were utilized in this undertaking. The
tower is 191 feet in height, and the light can be seen for about twenty
miles. During the past two or three years the United States Government
has erected two other noble lighthouses in Lakes Superior and Michigan.
The first warns all and sundry off a rock having three ugly pinnacles
projecting above the water, and known as the “Rock of Ages.” This
danger stands right in the steamship tracks between Port Arthur and
Duluth, off the western end of Isle Royale. The engineers selected one
of the pinnacles as the base for the tower, decapitating the projection
to 12 inches above mean low-water, so as to secure a sufficiently
large and level plinth. On this bed a cylindrical foundation pier, of
massive proportions and strength so as to withstand the ice action, was
planted, to support a lofty tower in reinforced concrete. The building
has seven floors, one being set aside for housing the two twenty-four
horse-power oil-engines which are used to drive the air-compressors
for the fog-siren. The light is 125 feet above water-level, and
gives a double flash at ten-second intervals, which can be picked up
twenty-one miles away. This tower was erected in a very short time,
the work, commenced in May, 1907, being completed, except for the
installation of the permanent lens, thirteen months later. The optical
apparatus was fixed and the light shown first on September 15, 1910.
The second light has been placed on White Shoal, at the north end
of Lake Michigan, and supersedes a lightship which fulfilled all
requirements for many years. The shoal is exceptionally dangerous, and
the crowded character of the shipping demanded the installation of a
more powerful light and fog-signal. The structure is a striking piece
of work, comprising a steel cylindrical tower, or shell, lined on the
inside with brick and faced externally with terra-cotta--an unusual
material for lighthouse construction. The superstructure is built
upon a massive concrete pier, about 70 feet square, rising 20 feet
above water-level, this being borne in turn upon a heavy stone-filled
timber crib laid on a block-stone foundation, the whole being protected
thoroughly with riprap. The lantern is of the second flashing order,
with the focal plane 125 feet above the lake-level, and the 65,000
candle-power ray is visible twenty-five miles away. The tower is
fitted with a duplicate plant of twenty-four horse-power oil-engines
and air-compressors, operating an eight-inch whistle; and there is
also an electrically-operated submarine bell, the power for which is
generated by an independent oil-engine, the bell being operated from
the engine-room. This station is equipped also with a compressed air
water-supply system and a motor-boat.
[Illustration: THE LATEST DEVELOPMENT IN LIGHTHOUSE ENGINEERING.
Building the hexagonal tower on Caribou Island, Lake Superior, upon the
lines evolved by Lieut.-Col. W. P. Anderson, the chief engineer to the
Canadian Lighthouse Department.]
Owing to the peculiar prevailing conditions, the provision of adequate
beacons upon the Great Lakes is highly expensive. Up to the year
1883 more money had been devoted to the lighting of the shoreline of
Lake Michigan than to the illumination of any ocean or gulf in any
other State in the country. The total expenditure up to the above
year exceeded £470,000, or $2,350,000. The Spectacle Reef light
was considered cheap at £75,000, or $375,000; and the Stannard Rock
lighthouse, owing to the plant and other facilities being available
from the foregoing work, cost £60,000, or $300,000. By the time the
“Rock of Ages” tower threw its light, £27,649, or $138,245, had been
sunk; and the White Shoals lighthouse absorbed £50,000, or $250,000.
The Canadian Government, too, has completed some notable works upon
the Great Lakes during recent years. In Lake Erie, in the fairway of
passing traffic, is a ledge known as Colchester Reef, on the south-east
edge of which a lighthouse, one of the most isolated in Canadian
waters, has been placed. The circular stone pier is built in 14 feet of
water, and the lighthouse, comprising a two-story dwelling and tower,
supports the beacon 60 feet above the lake. The light is a fixed white,
of the third dioptric order, visible throughout a circle of fourteen
miles radius.
At the entrance to Parry Sound, on a convenient site offered by the
solid granite mass of Red Rock, a new lighthouse was constructed in
1911. This was the third beacon placed at this point, the two previous
lights dating from 1870 and 1881 respectively. It is a particularly bad
spot, since the waters of Georgian Bay have a free run, so that the
rock experiences the full hammering of the sea. The beacon comprises a
reinforced concrete building, nearly elliptical in section, supported
upon a heavy stone foundation, which is encased in steel, and which is
12 feet high. The tower has a height of 57 feet, bringing the occulting
flash of twelve seconds, with an eclipse of four seconds, 60 feet above
the water. This station is also equipped with a powerful diaphone. The
keepers of this light experience exciting times, as in a furious gale,
such as the lakes only can produce, the waves frequently crash over the
building.
Another fine light in the stretch of these waters under Canadian
jurisdiction is found about halfway across Lake Superior, where
Caribou Island thrusts its scrub-clothed hump above the water, almost
directly in the path of the vessels running between Sault Ste. Marie
and Sarnia. This magnificent structure, placed on a small islet lying
off the main island, is built in ferro-concrete, in accordance with
Lieutenant-Colonel Anderson’s latest ideas, and was opened for service
in 1912. It is of hexagonal shape, with six flying buttresses, and the
focal plane is brought 99 feet above the water-level, so that the white
flash of half a second may be seen all round from a distance of fifteen
miles.
The steamship lanes across the Great Lakes are now well lighted. Canada
alone maintains over 460 lights of all descriptions throughout its
waters between the eastern extremity of Lake Ontario and the head of
Lake Superior at Port Arthur. The United States authorities watch over
694 attended and unattended aids to navigation in the same seas, of
which total 152 are scattered around the coastline of Lake Michigan.
The mariner in these fresh-water oceans, consequently, has a round
thousand lights to guide him on his way, and the number is being
steadily increased to keep pace with the growth of the traffic, so that
these seas may become regarded as the safest and best protected in the
world.