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Canadian Historic Sites: Occasional Papers in Archaeology and History No. 12
Lime Preparation at 18th-Century Louisbourg
by Charles S. Lindsay
Other Lime-kilns at Louisbourg
At least six lime-kilns besides the one in the faubourg are
known to have existed at Louisbourg during the French occupation (Fig.
22). In probable chronological order they are:
1) Two lime-kilns (Fig. 23, a) built astride the line of the
King's-Dauphin curtain. These were built for the construction work on
the King's Bastion and Barracks, and had been demolished by the time the
curtain wall was begun in 1735. Nothing is known about the kilns beyond
the plan drawings and the accompanying view (Fig. 23, b). Except
that they were square based, not circular, they appear to be standard
types as shown in Figure 1, 3, 4, good examples of kilns erected
near the site of the construction work.
2) The Royal Battery lime-kiln depicted in a detailed view of the
construction work there in 1725 (Fig. 23. c). The view shows the
top of the kiln projecting approximately 6 ft. above the surface, and
also shows the slaking pits. The date of destruction of this kiln is not
known, but it probably was abandoned when construction of the battery
was finished.
22 Distribution map of lime-kilns and slaking pits at Louisbourg.
1, Rochefort Point kilns and slaking pits; 2, kiln near
Block 46; 3, King's-Dauphin Curtain kilns and slaking pits;
4, possible slaking pits for Faubourg kiln; 5, Faubourg
kiln; 6, Royal Battery kiln.
(click on image for a PDF version)
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3) A lime-kiln built about 1737 just behind the King's-Dauphin
curtain west of Block 1 inside the town (Fig. 23, d). This kiln
seems to have been built to replace those that had been astride the
King's-Dauphin curtain. The owner of a nearby house, Joseph Lartique,
complained that the fumes from the kiln were ruining his health;
however, since this was the only lime-kiln in operation at Louisbourg at
the time, he had to put up with the inconvenience.1 The
lime-kiln was excavated in 1967 by William A. Westbury, and was found to
be a simple circular structure (Fig. 24). All that remained was that
part of the kiln that had been subterranean. The kiln was 23 ft. in
over-all diameter, with a wall 3.5 ft. thick, creating a furnace 16 ft.
in diameter. On the north side the wall thickened out at the drawhole,
the sill of which was 3 ft. above the dirt floor of the kiln. Outside,
the ground surface had been 5 ft. above the floor, so the stone-lined
passageway to the drawhole was approximately 2 ft. below ground
level.
23 Historical drawings of lime kilns at Louisbourg, a and
b, show lime-kilns astride the King's-Dauphin curtain. Taken from
a plan entitled "Plan Pour Servir as Projet Representé en Jaune du
Revetment du Quay du Port de la Ville de Louisbourg en l'isle Royalle,"
1731 (Archives du Génie); c, shows the Royal Battery lime-kiln.
Taken from a plan entitled "Plan de la Batterie Royale Avec Ses Environs
Pour Servir au Projet de 1726" (Archives Nationales); d, shows
the kiln west of Block I. Taken from a plan entitled "Partie de la Ville
de Louisbourg" (Archives Nationales); e, shows the lime-kilns at
Rochefort Point. Taken from a plan entitled "Louisbourg 1752; Plan de la
Pointe à Rochefort" (Archives Nationales); f, shows one of the
Rochefort Point kilns. Taken from a plan entitled "Plan du Cap breton
dit Louisbourg Avec ces environs Pries par Lamiralle Bockoune le 26
juillet 1758"
(Library of Congress).
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A U-shaped iron band with short horizontal terminals at either end
lay on the floor of the kiln. The length from apex to terminal was 2 ft.
This band would have adequately served as a support for the arch of the
drawhole.
From the remains this kiln appears to have been very similar to the
flare kilns from Provence (Fig. 3, a). The floor some distance
below the sill level, the shallow sunken passageway, the cylindrical
furnace and the free-standing walls all point to the Provence kilns as
the prototype for this one.
4) Two kilns at Rochefort Point, outside the eastern defences of the
town, have a rather vague history both in place and time. Various maps
show the kilns at different places, but the most probable site is near
the harbour side of the point on a low rise to the east of the pond in
front of the Maurepas Bastion (Fig. 23, e). Although the erection
of these kilns was proposed in 1738, they do not appear on any plans
until 1745 but are described as "old lime-kilns" in 1746.2
They were still in existence in 1758, but it is not known whether they
were still in operation at that time. An interesting, if somewhat
impressionistic, view of the area in 1758 shows one of these lime-kilns
(Fig. 23, f). In appearance it is almost exactly similar to that
in Figure 1, 11, but seems to be free-standing rather than
subterranean.
Little is known about the operation of lime-kilns at Louisbourg,
though something can be inferred from incidental remarks by Franquet in
letters to the Minister of Marine in France.
In a highly critical account of the cost of
lime-burning, Franquet, in 1751, stated that the lime-kiln
(at this date almost certainly one of those at Rochefort Point)
was badly built, would hold only 2.25 cubic toisés of
limestone, and was poorly serviced by the soldiers.3 This same
account describes payments made to the soldiers for operating the
kiln. They were paid for, among other things, constructing an
arch in the kiln 5 pieds high and capable of taking
the weight of the limestone. This indicates that the kiln was
being fired as a flare kiln. In a later passage he notes that if
the kiln were well-built, it would not need such an arch,
suggesting that he thought that a "well-built" kiln should be
fired as a running kiln. The soldiers were also paid for
breaking the stone, loading the kiln, watching and feeding the fire day
and night and removing and slaking the lime. Three men were
occupied at this task for 11 days and the 4 nights when the fire
was alight and had to be constantly tended.
Franquet's major complaint about the lime-burning was centred around
the incompetence of the men operating the kiln. He noted that as much as
one-fifth of each load was unburned because the stone was not properly
broken and loaded, so the heat could not penetrate completely. Also the
arch, being badly built, often collapsed during the firing, ruining the
load of limestone.
Documentary and archaeological evidence show that both wood and coal
were used as fuels at Louisbourg. In 1718 it was noted that mortar used
in waterlogged areas was mixed with the ashes from the coal with which
the lime was burnt.4 In 1752, Franquet suggested as an
economy measure that coal be used for burning the lime instead of wood
and fascines as had been used at the Royal Battery kiln.5 The
surface of the passageway to the entrance of the first kiln in the
faubourg was covered with crushed charcoal fragments. The ground
surface outside the passageway, on top of the continuation of the raised
floor level to the second kiln, contained, among some boulders of partly
burnt limestone, some fragments of coal and charcoal. Since secondary
sources suggest that coal is used only in running kilns, the appearance
of coal fragments associated with the second kiln reinforces the
argument for interpreting this as a running kiln.
Since the cost of lime had risen from 4 livres per barrel in
1725 to over 8 livres per barrel in 1751, Franquet wanted to
initiate savings which he suggested could be made by the use of coal
instead of wood, burning the lime at the limestone quarries, and slaking
it before transport to the construction site. Since the limestone
quarries were at Spanish Bay (Sydney), 26 miles away. and Main-à-Dieu,
12 miles away, the transport of liquid lime would have been a major
problem. Nonetheless, Franquet insisted that it could be done after the
lime had been allowed to settle a little. We do not know whether
Franquet succeeded in convincing the minister of the feasibility of his
scheme.
24 Remains of the excavated lime-kiln west of Block I.
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