The Prince of Wales Tower is a well known monument in Point Pleasant Park. It was one of 16 similar towers built in Canada. Of the 16 built,  five were built at Halifax; one at Saint John, New-Brunswick; four at Quebec City: and six at Kingston. The Kingston towers are the newest, built 1846-48. The remainder were built between 1796 and 1815; Three of the Halifax towers predate the “Martello Tower” name and concept and were built between 1796 and 1799.

The Martello tower was a fortification built in the south of England during the Napoleonic wars, around 1805-1808. The basic definition is a circular tower of brick or stone construction used for coastal defence. The name is derived from a stone tower on Cape Mortella in Corsica which was defended against English naval attack. That tower was designed by Giovan Giacomo Paleari Fratino and built in 1565.

The standard Martello tower is stone, 2 stories high, with a terreplein on top designed to take armament. (A terreplein is the topmost horizontal surface of a fortification designed to take guns.) The towers are constructed of arched spaces around a central pillar to improve bomb resistance, and are 35′-55′ feet across depending on the number of guns to be mounted.

The Prince of Wales Tower was the first, and thus differs from the accepted design. Commissioned by Edward, Duke of Kent, it was built by Captain Straton, Edward’s Commanding Royal Engineer. The tower was intended to back up the batteries in Point Pleasant, and was begun and 2/3 complete by the end of 1796. That’s when Edward ran afoul of regulations. As a field commander, Edward had the ability to build temporary fortifications; however, permanent fortifications required the approval of the board of ordinance. Construction was halted until the end of the 1797 building season, after Edward got approval from the board. The tower was completed in 1799, but was defensible from 1797.

The completed tower is built from rubble masonry, and is 72′ in outside diameter. It is 26′ tall, and the walls are 8′ thick at the base, 6′ thick at the top. There were 2 interior stories, topped with a 3 foot thick wooden roof. The roof was supported by a 16′ diameter hollow column, that extended to the foundation, leaving a 16′ room on each level.

As built, the tower differed from what would become the standard in several significant ways – it lacked a magazine of its own, the bomb-proofing structure was not included, and its large dimensions. Work to rectify this began in 1805, with the addition of a magazine, and in 1810, the wooden terreplein was replaced with a bomb-proof arch. As originally built, entry was via spiral staircase on the exterior, and through hatches in the terreplein.  The ground level door likely was added in 1805 when the magazine was added on the ground floor. In 1862 a basement magazine was built in the Prince of Wales Tower, the idea that it would be more economical then a separate magazine, and meet the needs of the Shore batteries there. The upper door was added at this time, ensuring the tower could be accessed without interfering with the magazine.

The second tower was at Fort Clarence, where the Imperial Oil Refinery now stands. Originally intending to be a blockhouse, Edward decided to build a round tower instead. The tower was 50′ in diameter, 42′ high from foundation to parapet, with 6′ thick walls. it was completed in 1798. The tower when built was 3 stories tall, though the 1st floor was surrounded by a ditch and was below grade.  Access was via external iron staircase to the top. This tower also lacked bombproofing,  and the internal pillar was only 6′ in diameter.

In 1812, the external stair was removed, and a second level door added (this was ground level), reached by a drawbridge across the ditch. A magazine was built on the first level, but no bomb proofing was done.

By 1867 the upper floor was removed, and the middle turned into a barracks. A bomb-proof arch was installed in the basement, for conversion to a magazine. In 1889 the barracks floor was removed, leaving only the magazine.

The Third Martello tower was also built by Edward. Located at York Redoubt, it was 40′ in diameter, and 30′ high, with uniform 4′ thick walls. It was built of rough quarried stone, and was completed in 1798, replacing a blockhouse. The tower may have been chosen as it could carry heavier guns than the blockhouse. The tower also featured the hollow central column. The terraplein was constructed of wood, as was the parapet – unique to this tower. A bomb-proof magazine was added after 1811, but the tower remained unchanged until the 1860s.

A 1960 renovation added caponiers on either side. Caponiers are protruding galleries that allow muskets to be fired. These can be seen in the image at the top.

A fire in the 1890s destroyed the upper level of the tower, and the lower level was integrated into other defensive improvements at the Redoubt.

Tower 4, located on Georges Island, was the first true Martello tower in Halifax. Though the island had been fortified since 1750, defences were inadequate, and comprised mostly of earthworks. Under Edward, a star fort was constructed with a blockhouse before his departure in 1800, but it too proved inadequate.  The plan for this tower was approved in 1811, and construction began in 1812. It was well underway by July, and complete and armed by the end of the year.

As completed, the tower was 42 feet in diameter, with a 5′  solid central column. It was built of bomb-proof arched construction, 2 stories tall with terreplein and parapet. Walls were 7′ thick at the base. A brick magazine was located on the first floor, and there was an entry door on the ground level.

Sherbrooke Tower was the 5th tower. It was demolished in 1944, and replaced with the current concrete light at Maughers Beach. Begun in 1814, construction was slow due to the need to move materials to the site, and faulty estimates. The tower’s construction was halted in 1816 for 10 years due to the end of the war of 1812. Go-ahead was finally given to continue in 1827.

When completed, the tower was 2 stories, 50′ in diameter and 30 ‘ high, with walls 7′ thick at the base, diminishing to 5′  at the parapet. A solid 2’ circular central pillar supported a bomb-proof arch above the barrack floor.  In 1826, the NS Legislature voted to spend 1500 pounds on a lighthouse on the beach. Gustavus Nicolls, then Commander of the Royal Engineers, suggested the completed tower could be used. It was too remote for a barracks, and the province would cover a lightkeeper who could maintain the tower, at no cost to the military. When complete, it was pressed into service as a lighthouse. The intended platform guns were installed in 1827 before the wooden lighthouse superstructure was placed on top of the tower. This light room caused no conflict with the guns, as it was balanced on a single masonry king post rising from the centre of the platform. The lighthouse began operation in April 1828.

The towers frequently suffered from moisture problems, and were fitted with wooden conical snow roofs by 1824. Sherbrooke Tower was the first to receive the roof. It was intended that guns could be fired from under the roof, though the roof would be removed in the event high readiness was required. Maintenance varied, and the towers were all considered to be in fair condition owing to the fact the Halifax towers  were attached to the British Imperial Naval Station, post-confederation.

By the 1860s the towers were obsolete. Rifled munitions were more powerful and accurate then smoothbore cannons before. In tests in 1860 on the Sussex coast,  a Martello tower was destroyed with 27 rounds of rifled munitions. Smoothbore guns had a negligible effect on a different tower.

The Prince of Wales tower was turned over, intact, to the Canadian government in 1906, on the departure of British forces. The tower at York Redoubt was also well maintained as a signal post, though the upper level was destroyed by fire. It was roofed over, and also turned over to the Canadian authorities in 1906. The Tower at Fort Clarence survived as just the magazine until after the Second World War, when it was removed for refinery expansion. The Tower on Georges Island was demolished in 1877, as Fort Charlotte works were commenced.

A recent Noticed in Nova Scotia post touched on the aesthetics of the Robie Street Reservoir. Stephen Archibald mentions that the reservoir was built in 1913, and it has received new roofs twice – once in 1946, and again in 1999. Curiously, this simple tank has been quite the source of innovation.

Halifax water works on a high pressure and a low pressure system. Water is gravity fed in 24″ and 27″ mains for the low pressure system, and in 15″ mains for the high. In the Map above, the Yellow line divides the high and Low Service Areas.

The Robie Street High Service Reservoir was built in 1913 to provide supply and additional pressure to the high service. The site selected was known as Hungry Hill, and was the highest locally available spot.  The reservoir has an interior diameter of 160′, and is 25′ deep. The walls are 3′ thick at the bottom, tapering to 18″ at the top. The roof was almost flat, and was a 4″ slab supported by radial concrete girders and 53 18″x18″ posts.

By the mid 1940’s the Halifax water system had just about lived its normal life and was due for replacement. The population had increased from 70,000 to 130,000, and there were again issues with water pressure for firefighting.  An engineering report of the system was produced, and the Halifax Water commission was formed and set out fixing the system. The Robie Street reservoir included.

The reservoir was in bad shape. By 1945 the roof was close to failing completely, and chunks had fallen into the reservoir. The girders supporting the roof were failing at the shear points with the columns. The inside wall was worn down to rebar due to ice action. Ten inches of slime covered the floor of the reservoir. The outside wall suffered from spalling. The Water Commission decided to undertake repairs.

The old roof was removed, but the columns were retained. Loose material was chipped away from the inside, and the areas sand and water blasted.  Steel wire mesh was then anchored in place, and multiple layers of gunite were shot in place. Once the inside was done, the same process was done on the exterior.

Gunite was, at one time, a trademarked name that specifically refers to the dry-mix shotcrete process. In the dry-mix process, the dry sand and cement mixture is blown through a hose using compressed air, with water being injected at the nozzle to hydrate the mixture, immediately before it is discharged onto the receiving surface. The concrete mixture is by pneumatic pressure from a gun, hence “gun”-ite.

The roof dome at the time was the largest pre-stressed concrete shell in the world. At 3 inches thick, it was cast in place on forms, after the edge ring was cast. The dome took 5 days to pour, and work progressed around the clock, with two 12 hour shifts. The pre-stressing was accomplished by applying 180,000psi of force on a 0.162″ steel wire, and wrapping it around the ring 360 times, in 5 layers. A coat of gunite was applied between each layer, and in all 42 miles of wire were used.

The outside of the reservoir was finished with a white cement brush coat.

By 1999, it was time to replace the roof again. This time a lightweight aluminum geodesic dome was chosen. The existing roof was removed with explosives, which were also used to release the pre-stressed ring beam. Charges were set around the perimeter.

With the roof replaced, the Robie St. High service Reservoir can continue to serve the people of Halifax.