"Hypotheses are statements of relationships between two or more variables" and provide a premise from which to argue and draw conclusions (Plog 1974:18). A hypothesis offers a foundation for gathering facts to test an idea or phenomenon with a series of questions. Objectively, the hypothesis is supported or refuted on the basis of questioning, or comparing the expected against the observed reality. Often, however, the hypothesis is used as the controlling idea instead of a supposition to be tested. This leads to a fallacy when the accepted hypothesis is no longer valid (Chamberlin 1965:755-756).
Any single hypothesis may not explain a complex situation with a number of causal factors. For a maritime archaeological site, any number of agents contributed to site formation, some of them dating to the ship's first day of construction. By subjectively creating a group of multiple working hypotheses, a group of predictions about the site can be made. The predictions guide field work in an attempt to disprove them. This investigative methodology is used to examine the Maple Leaf site. Each hypothesis is presented in conjunction with an exclusionary, or null, hypothesis. The null hypothesis tests the validity of the proposed supposition by asking how to disprove it (Platt 1964:352).
Chapter two presented documentary material about the Maple Leaf. The historical sources allow me to predict archaeological evidence which is expected on site. Hypotheses derived from the historical data represent basic, general questions pertaining to the Maple Leaf's construction, operation, and loss. In this section, the historical data have been organized into a series of hypotheses which will be tested against archaeological findings. These hypotheses guided the field research on the Maple Leaf site.
The 1856 ambrotype (Figure 5) shows that the Maple Leaf's hull incorporated bishop arches, or hogging trusses, for longitudinal reinforcement. Hogging forces play an increasingly important role as wooden ship length increases. The elastic nature of wood over great lengths allows it to bend and flex if not equally supported along its length. A wooden hull also experiences differential support, or buoyancy, from bow to stern as the hull's shape changes. Maximum buoyancy occurs amidships where the hull is widest. Toward each end the hull narrows, reducing the surface area available for buoyancy support. As a result, the bow and stern tend to droop, or hog. Other factors influencing hogging include weight distribution of the cargo and machinery. Nineteenth century Great Lakes shipbuilders had several techniques to counteract these forces in order to support the ends and keep the hull rigid. The reinforcements included diagonal iron strapping, diagonal ceiling planking, plank arches built into the hull, and bishop arches or hogging trusses (Dorr 1876).
Historical and archaeological sources describing hogging truss construction on the Great Lakes are sparse. Bates (1968) discusses support systems used on shallow draft western river steamboats. Their athwart ship support principles are similar to those used on the lakes but river boats did not use heavy longitudinal arch supports. Instead, western river steamboats utilized hogging chains, a system of iron rods and turnbuckles, for longitudinal support. Archaeological evidence from Great Lakes shipwrecks describe plank ceiling arches that are built into hulls such as the Cumberland (Murphy et al. 1987:231) and Bermuda (Labadie 1989 42-43). Few shipwrecks with hogging arches have been thoroughly investigated (David Cooper, personal communication, 3 November 1994).
Shipbuilding rules adopted by the International Board of Lake Underwriters in 1876 describe hogging truss construction in detail. The rules specify that the arches "pass through the [main] deck and extend down the ceiling quite to the apron forward, and the inner post aft..." (Dorr 1876:69-70). The layered timbers forming the arch are joined by lock scarfs reinforced with threaded bolts, nuts, and washers. Posts supporting the arch are inserted between the frames and extend to the bottom of the deck clamp. Below deck the arches are bolted through every strake. Above deck they are braced and tied athwart ship to prevent transverse movement (Dorr 1876). These construction features link the truss with the keel and keelson, the main longitudinal elements of the ship.
Hypothesis 1 states: the hogging truss fastens with the keel and keelson. To disprove the hypothesis, the truss must fasten to other parts of the ship besides the keel and keelson or to parts of the vessel not linked to either the keel or keelson.
The Maple Leaf's superstructure will not be found on the site. It was lightly built relative to the hull. This hypothesis is sub-divided by the two possible agents that caused the destruction.
H2o: The null hypothesis, the superstructure will be intact.
H2a: The superstructure was destroyed by natural weathering and decomposition processes.
H2b: The superstructure was destroyed by Roderick Ross' demolition work to clear the navigation channel.
After the Maple Leaf sank, Confederate forces shelled and burned the exposed saloon deck (Anderson 1864; Bryan 1864). The extent of destruction caused by this activity is not known but the submerged superstructure escaped damage. For nineteen years tidal currents, storms, and marine organisms affected the Maple Leaf before Roderick Ross worked on the site in 1883. An inspection of the site completed that year stated little of the cabin structure remained (Russell 1883). Under the terms of his contract, Ross had to remove any remaining cabins posing a threat to navigation.
Hull strength was paramount for a vessel's safe, useful, working life. Storms, ice, groundings, and collisions were common hazards leading to ship loss. A strong hull helped absorb some of this abuse. The cabin superstructure had little bearing on hull integrity. During a normal working life, the superstructure was not subject to the same wear as the hull. A builder could make the superstructure functional and aesthetically pleasing without spending additional funds to make it strong. Therefore, except in extreme cases such as shipwrecks, cabins functioned well enough without the extra heavy construction.
Reports of vessels lost on the Great Lakes often refer to cabins coming off during shipwrecks or bad storms (Labadie 1989:36, 46, 54, 76, 110, 123, 141, 150, 154; Murphy and Holden 1987:88, 90; Murphy et al. 1987:217). This usually occurred in one of two ways. First, by being battered and knocked off by waves as the vessel sat grounded in a storm; second by air trapped inside a sinking vessel. Depending on the speed of the sinking, increasing air pressure could cause the cabin to tear loose or literally explode from the hull.
Examples from contemporary sources describing the loss of cabins seem to confirm their lightly built nature. Storm generated waves swept the saloon cabin off the steamer Algoma after she ran aground on a reef in Lake Superior. "As soon as the hull became fast on the rocks, the force of the waves dashing in fury against it soon broke up the saloon, and swept it away" (Owen Sound Times, 19 November 1885). The schooner Bermuda lost her cabin when she suddenly sank while moored in a protected anchorage. "All hands were carried down with her, and but for the bursting of the cabin deck, none would have been saved" (Detroit Post, 20 October 1870).
The Maple Leaf site will produce few or no decorative embellishments from the superstructure's cabins. The ship was contracted for military use and later subjected to natural and human demolition. Decorative embellishments can be divided into two classes; portable furnishings and non-mobile architectural elements. The hypothesis has been sub-divided to include the null hypothesis and the two decorative classes.
H3o: The null hypothesis, all decorative embellishments will be present.
H3a: Portable decorative furnishings were removed prior to military service.
H3b1: Non-mobile decorative architecture was removed in converting the ship to military use.
H3b1-a: The vessel was modified for military personnel and cargo.
H3b2: Non-mobile decorative architecture was lost when the cabins were removed.
Contemporary historical sources describe the Maple Leaf's cabins as highly embellished. Cabins were "richly decorated with white and gold cornices, and paneling, the chairs and settees cushioned with crimson plush, and curtains of crimson and gold damask. [A] profusion of stained glass...[covers] every door and window with pretty sketches enwreathed with maple leafs" (DBW 26 March 1851).
Non-structural decorative elements, including furniture and drapes, probably disappeared when the ship entered military service and were not on the Maple Leaf when it sank. There was no reason to keep and incur the cost of maintaining these features while the vessel operated under military charter. The owners did not need to appeal to commercial customers or maintain an attractive ship.
Architectural elements, such as decorative woodwork and stained glass windows, remained on board during military service. Removing and replacing these fixtures with more mundane pieces would only increase costs. These fixed architectural features were probably on the ship when it sank. As the riverine environment and Ross' 1880's work demolished the cabins, the architectural features were probably destroyed. If decorative architectural elements were on the vessel at the time, they will be present in fragmentary form on the deck.
Use as a transport might require removal or modification to the cabins to house and transport large numbers of troops and their equipment. The Maple Leaf's last two missions involved transporting large deck cargo. The trip from Folly Island, South Carolina to Jacksonville, Florida, included thirty-two horses, four wagons, and four carts (Hyde 1866:60-71). Then the ship moved seventy-five cavalrymen, eighty-seven horses, and horse feed to Palatka, Florida (Walbridge 1864b). Such a large number of horses, wagons, and carts required considerable open deck space. This suggests the superstructure was already modified to carry large scale cargos on the main deck.
The Maple Leaf's hull was sheathed with copper for service on saltwater. To disprove this hypothesis, no copper sheathing can be found.
Wooden ships operating in warm saltwater were exposed to damage by wood boring mollusks, or ship worms, and fouling by barnacles. To prevent this, the British began to sheath hulls in copper by the late eighteenth century (Anonymous 1763). To prolong the ship's life, the Maple Leaf was probably sheathed in copper soon after it entered saltwater service. This sheathing will be found on the lower hull.
The Confederate torpedo explosion damaged the bow area, especially the lower hull. For this hypothesis to be supported, evidence of torpedo damage must be found. To disprove the hypothesis, no damage attributable to the torpedo will be found. Testimony taken after the Maple Leaf sank describes tremendous damage caused by the torpedo explosion in the bow area (Murray 1864). The torpedo exploded under the ship about thirty feet from the bow on the starboard side (Farnham 1864). Presumably, most torpedo damage, including a large hole, occurred on the bottom and/or side of the hull. This damage would only be apparent at the bottom of the forward cargo hold or on the ship's hull below the deck.
The explosion's force did cause damage above the main deck level. As crew members abandoned ship, they noticed the forward mast had fallen forward and that the pilot house was collapsed (Murray 1864). The falling mast certainly damaged the mast partners and possibly fractured nearby deck beams. The explosion also broke the forward end of one hogging truss (Farnham 1864). Evidence of this break was probably obliterated by natural weathering or demolition in the 1880's.
Although the rest of the ship remained unharmed by the torpedo, Confederate forces inflicted further damage soon after the sinking. Two days later they shelled the wreck and set fire to the exposed saloon deck rising out of the river. This damage was minor and limited to the superstructure (Anderson 1864, Bryan 1864).
The Maple Leaf was salvaged after it sank. Any salvage operations will be indicated by evidence, both positive and negative, found on the site. This hypothesis can be divided further by the type of salvageable material on board.
H6o: The null hypothesis, no salvage occurred.
H6a: The cargo was salvaged.
H6b: Ship components were salvaged.
The lost cargo of sutler stores and soldiers personal effects had no impact on the war effort and therefore held no appeal for salvage by the Federal government. This material did offer the local population a tremendous opportunity. Although there is no historical documentation, local citizens probably took everything off the ship they could easily carry. The extent of this type of salvage effort is not predictable. It may be limited to the superstructure or the hull may have been breached to enter the cargo holds. While evidence of salvage in the superstructure is not expected, any attempt to enter the cargo holds, except through hatchways, probably damaged the deck.
On a larger scale, the Maple Leaf contained a valuable engine, propulsion machinery, and assorted deck equipment. Salvage of these materials would require financing, vessels, equipment, and manpower. Historical documents mention two planned or attempted salvage operations (Hatch 1864c, Stillwell 1865). A successful salvage would be evident by conspicuously missing ship components. Deck equipment, such as anchors, windlass, and capstan, would be the easiest to retrieve. Engine and drive train salvage would require a major effort due to weight and size. Besides being absent, their removal would be indicated by damage to the ship’s machinery mounts and support structure.
The site was extensively damaged by demolition work in the 1880's. This hypothesis is sub-divided into categories. Much of the same evidence applicable to hypothesis 6 also applies to hypothesis 7, but for different reasons.
H7o: No demolition work occurred.
H7a: The steam engine and propulsion machinery were damaged or destroyed.
H7b: The ship's structure was damaged or destroyed.
The United States Army Corps of Engineers hired Roderick Ross, a marine contractor, to clear obstructions from the channel to a safe depth for river navigation. Ross used explosives to break-up major ship components including the gallows frame, bishop arches, and paddle shaft. Some of these pieces were reportedly pulled off the site and deposited in the river or on the shoreline (Russell 1883).
In the archaeological record, these components should be damaged, destroyed, or completely missing. Damage to surrounding areas of the ship should also be evident, especially in the engineering spaces where most machinery was located. Ross' demolition work may account for other structural damage not mentioned in historical sources.
The Maple Leaf's structural remains are well preserved by anaerobic sediments. This hypothesis can be further sub-divided into wood, metal, and glass. Twenty-five other types of material have been identified, primarily in the cargo (Lee B. Manley, personal communication, 1 November 1994), but they have little or nothing to do with the ship's structural fabric, thus they are not relevant to this hypothesis.
H8o: The null hypothesis, nothing will be preserved.
H8a: Wood will be well preserved
H8b: Metal will be well preserved
H8c: Glass will be well preserved
Following Ross' work on the wreck in 1889, the Maple Leaf remained undisturbed for ninety-six years. During the interim period, sediment covered most of the wreck to a depth of four to eight feet, creating an oxygen free environment. Anaerobic conditions provide excellent preservation for organic and inorganic materials because the oxygen-free environment will not support organisms that destroy organic artifacts (Singley 1988:6). Glass and ceramic are inorganic and nearly unaffected by the site environment. Electro-chemical processes responsible for metal corrosion persist, although at a slower rate, including galvanic coupling and iron corrosion caused by sulfate reducing bacteria and methogenic bacteria (North and MacLeod 1987:75-76; Rodgers 1989:336). In general, those portions of the wreck that survived early exposure to the river and Ross' demolition work should be well preserved under the river bottom.