Before proceeding to a discussion of the supply and demand of marine engines in central Canada, it is important to get an overview of the technology being used. (16) Examples drawn from Great Britain, the east coast of the United States, and the Mississippi and Ohio rivers represent the rest of the "known universe" of steam engine designs so far as central Canadian investors were concerned. In these regions a variety of opinions were held as to the most efficient way of transforming steam into vessel movement.

Throughout the previous century, "atmospheric" steam engines of the type developed by Thomas Newcommen had been used in Britain, usually to pump water. These were massive brutes guaranteed to break the back of any keel on which they were placed. James Watt's principal contribution was to attach a condenser to the side of the cylinder, which was connected by a sliding valve to both sides of the piston. The result was faster piston motion, allowing great power to be produced by a smaller, lighter-weight cylinder. Its greater fuel efficiency made it better adapted for vessels which, unlike stationary engines, also had to carry their fuel supply. (17) However, it would take a North American to convince the world that "fire engines" and ships could be profitably combined.

In the first decade of the nineteenth century, the most complicated "machines" built in the Canadas were probably water-powered saw and grist mills and the square rigged vessels being launched from Quebec shipyards. (18) But these were principally built of wood, the iron fittings being critical but relatively unsophisticated. By contrast, the typical products of the forge and tinsmith were horse shoes, nails, barrel hoops, and pipes. The most elaborate mechanical contrivances of the era, such as clocks or firearms, were rarely produced in the provinces. (19) Consequently, the requirements of the steam engine represented a quantum shift in the sophistication of the products of metal working in the Canadas.

Figure 1: The Frontenac was powered by a fifty-horsepower, single-cylinder, crosshead engine built by Boulton & Watt. (Source: Birmingham Public Library, Boulton & Watt Collection, ff. 1213-1214)

For shipping, Boulton & Watt abandoned the overhead beam of their early stationary engines. Eminently suitable for pumping out mines, the ponderous beam engines pivoted on solid walls or frames which would have risen well above the main deck of a ship. Instead they developed an arrangement of crosshead, connecting rod and either side-levers or cranks intended to keep the bulk of the engine low in the hull of the vessel. Arrangements like those for the Frontenac (seen in figure 1)were designed for navigation in fairly boisterous seas, where they contributed to the stability of the craft. The vertical movement of the piston rod was transferred to the cranks or side lever via a crosshead working up and down in slides. The arrangement required very careful machine work and was prone to getting out of alignment.

The firm's boilers were only suitable for fairly low pressures-- 7 to 8 pounds per square inch (psi). Described as a "wagon" style, they were square bottomed with very large flues--large enough for a man to climb inside to clean them. Even at these low pressures, the poorly sealed joints could give, exposing the engine crew to a scalding. (20)

Because of Watt's healthy respect for the dangers of steam under pressure, his engines worked on the principle of condensation, rather than expansion of steam. Steam was introduced into the cylinder just as the piston completed its stroke. At this point a valve opened allowing that steam to exhaust into a condenser where it was cooled. As its temperature dropped, a vacuum formed, pulling the piston to it. Meantime on the other side of the piston, the cylinder was filling with steam, which might impart a modest bit of momentum to the piston. The movement of the piston rod was connected with pumps that forced cold water into the condenser and air out. The whole apparatus was relatively ingenious, but still weighed tons. Moreover, by limiting the pressure of the steam, the principal means to improve the power of the engine became increasing the diameter of the cylinder and piston and the length of the stroke. (21)

In the well developed harbours of Great Britain the tremendous weight of this machinery was not a significant problem. But, in North America, steamboats were operating on the frontiers, serving villages with crude landing stages or just lying up against the banks of a river like the Mississippi. The first priority of an engine builder on the western rivers of the United States was to help the shipwright maintain a shallow draft in a vessel powerful enough to fight its way upriver. There, engine builders quickly adopted Oliver Evans' high pressure, non-condensing engines. Light and powerful these could be, but such advantages had to be balanced against the greater risk from boiler explosion. The pressure in the boilers was allowed to build up well beyond the atmospheric level--usually about 60 to 80 psi, though rarely beyond 200. (22) Inside the narrow cylinder, the pressure of the steam pushed the piston one way until a valve opened to release it. The sound of steam being exhausted into the atmosphere was quite distinctive. As the approach of one vessel (whose Boulton & Watt engine had been replaced by two 120 h.p. high pressure engines built in Cincinnati) was described: "... the United Kingdom still holds out firm as a rock, grumbling, snoring and puffing off her surplus steam, to the annoyance of fiscal fish and ducks...." (23)

One of the problems with the massive low pressure cylinders stemmed from the common assumption that they needed to be kept vertical. Lay the apparatus on its side, founders reasoned, and the heavy piston would steadily wear away the lower wall of the cylinder until a vacuum could not be produced--no vacuum, no motion. But the cylinders and pistons in high pressure engines were comparatively small and light, allowing the engine to be placed horizontally, the only practical direction for driving sternwheels.

Similarly, Mississippi boilers quickly shrank into fairly compact cylinders--these being considerably stronger than Boulton & Watt's "wagon" style. Although smaller tubes would increasingly be used in place of flues on eastern steamboats, tubular boilers were more difficult to clean. And Mississippi mud was considered responsible for a number of the fatal boiler explosions on that river system. (24)

In Upper and Lower Canada, steamboats faced different problems. Muddy or salty water was not among these, so boiler cleaning was a relatively minor concern. And, apart from vessels on the Great Lakes, they operated on sheltered rivers and long narrow lakes so the demand for low centre of gravity was less pronounced. Moreover, with some exceptions, the need for shallow draft vessels was not as serious as on the Mississippi tributaries, although the governing depth of most ports of call was a mere six or seven feet. More than anywhere else in the world, these conditions resembled those facing steamers working out of New York City. The St. Lawrence steamers had their counterparts on the Hudson River, while the Great Lakes vessels could draw inspiration from the steamers designed for Long Island Sound. Not surprisingly, the technology of engine building for central Canada formed a continuum with that used in the eastern United States.

The type early favoured on these waters was closely derived from the Boulton & Watt engines imported by John Molson and Robert Fulton. Fulton preferred the crosshead style of engine with the connecting rods from the crosshead working a side-lever for his Hudson River vessels. (25) The crank-crosshead-connecting rod variation was supplied by Boulton & Watt for the Malsham, Car of Commerce and Frontenac of the St. Lawrence and Lake Ontario. (26) The principal complaint about this arrangement was the difficulty of getting the slides in which the crosshead moved perfectly true, and then keeping them that way. (27)

Figure 2: The Beam Engine of the Atalanta, built in New Jersey, 1816. (Source: Jean Baptiste Marestier, Memoir on Steamboats of the United States of America (Mystic, CT, 1957), figure 31.)

The archetypical eastern steamboat engine dispensed with the tricky crossheads and used the beam that was common in Newcommen and Watt's early engines.(see figure 2)There is some disagreement as to the original application of the walking beam to marine engines. Some claim that Daniel Dod, of New Jersey, used it in his patent engine of 1811. (28) Others give the credit to Robert L. Stevens, also of New Jersey, for a design dated 1822. (29) The principal concern with walking beams in England was a massive beam rocking back and forth well above the deck. To others it must have seemed much less risky than carrying a full press of sail on towering masts. The criticism, almost reflexive in many modern accounts, ignores the fact that significant improvements in both design and materials were made. Skeletal iron beams replaced the heavy wooden beams strapped with iron. By 1830 walking beams contributed to the distinctive silhouette of the majority of steamers in the eastern United States and central Canada.

Figure 3: Sketch of the boilers of the Dolphin (ex. Black Hawk)

The persistence of the low pressure "wagon" style of boiler for the period before 1838 is unclear because Canadian and American engine builders have not left us any sets of plans comparable to those in the Boulton and Watt archive. However, other evidence suggests that by the beginning of the 1830s, cylindrical boilers with internal flues were more typical. (30) At least two vessels were equipped with "railway" tubular boilers like those in figure 3, with larger numbers of smaller flues or tubes carrying the heat of the furnace through the centre of the boiler. (31)

Two patterns evolved for the placement of the boilers. The "English plan" was to place them in the hold next to the cylinder, where the weight of the boiler and its water helped stabilize the hull, particularly in rough water. (32) The alternative was to place them "on the guards" by the paddle wheels. Not only did this supply a better draft for the fire (and consequently better fuel consumption), but if they exploded, damage to the hull might be reduced. (33) There is only occasional evidence of lakes vessels adopting the latter plan.

The principal innovations in the low pressure condensing engines lay in stronger boilers and the perfection of the valves and action of the condenser in order to achieve more strokes per minute. (34) If steam pressure was held relatively constant, increased power could only be achieved by expanding the diameter of the cylinder and the length of the stroke (the efficiency of cutting off the stroke coming somewhat later). The market demand for engines of greater and greater power led to massive castings, which in turn necessitated a strong foundation plate to distribute its weight over the keel and keelsons. In 1832, Wards'Eagle Foundry produced the engines of the John Bull, two 60" cylinders with an 8 foot stroke. Using the Boulton & Watt formula for calculating power, they provided 150 horse power working at 15 psi and 20 rpm. (35)

If the owners wanted to operate a steamboat on waters where draft was critical, two alternatives were considered. Some vessels, like the Brockville and the Sir Robert Peel used low pressure, horizontal engines despite the risk of uneven wear. (36) The other alternative, unpopular in many quarters, was to use "high pressure" (non-condensing) engines, sometimes in combination with stern- or centrewheel arrangements. These were typical on the shallow waters of the Kawarthas, Lake Simcoe, the Grand River Canal and the Thames River after 1832. (37) Typically, these engines were imported from the United States or built by smaller foundries who dabbled in stationary engines. (38)

Of shafts and paddlewheels, little has to be said. Breaking shafts were a major cause of mechanical breakdowns. (39) The solution, for those who could afford it, was to stop using Canadian-made, cast iron shafts. Instead wrought iron shafts would be imported from Glasgow which local engine founders would incorporate into their products. (40) Although sidewheelers, sternwheelers and centre-wheelers were all tried, the real progress in propulsion belongs to the era of the screw propeller and the feathering paddlewheel.

The process by which the improvements had been achieved was one of constant innovation. As one observer described the process:

"They have effected this great increase of speed [from 5 mph to 15 or more] by constantly making experiments of the form and proportions of their engines and vessels, in short, by a persevering system of trial and error, which is still going forward; and the natural consequence is, that, even at this day, no two steam-boats are alike...."(41)

With imperfect knowledge of most of the engines built in the region, it is very difficult to trace the thoughts and contributions of each engine builder. However, a number of them were well travelled, inquisitive men. We know, for example, that John Dod Ward was in England in 1829, and his brother Lebbeus in 1837. (43) While John was across the Atlantic, a third brother, Samuel, travelled south to Washington, visiting a friend of the family at the United States Patent Office and commenting on a locomotive building in Baltimore. (44) They were also keen observers of what the local competition was building, and of the performance of their own work.

In general, the development of steamboat technology in central Canada moves in step with that of the eastern United States. The dependence on low pressure boilers, the walking beam engine and the side paddlewheel was characteristic of both regions.

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