Morey's first patent, in 1793, was for a steam - powered spit, but he had grander plans. Morey realized that steam could be a power source in the 1780s, and he probably appreciated a steamboat’s potential from work on his father’s ferry and the locks he designed along the Connecticut river. In the early 1790s he fitted a paddle wheel and steam engine to a small boat and powered it up and down the Connecticut River. Legend has it, this was done on a Sunday morning, when the town was at church, to avoid ridicule if he failed.

The most important aspect of this craft was the paddle wheel. It was an old idea – supposedly dating to antiquities – and previously tried with a steam engine. Jonathan Hulls of England used a rear - mounted paddle wheel in 1737 but an inefficient method of turning the steam engine’s reciprocating motion into the circular motion hobbled it. In 1789, Nathan Reed of Massachusetts experimented with a paddle wheel, and considered patenting it, but eventually patented a different method instead. The American John Fitch experimented with side - mounted paddle wheels, but in 1791 used and patented oars instead. Thus, Morey’s may have been the first successful use of a steam power paddle wheel, which was the best method of propulsion until the propeller, invented by Fitch, was perfected.

Morey’s first boat was little more than a proof of concept, so he built another in New York. In a letter to New York legislator William Duer, Morey describes how over the next three summers he traveled down to New York, and the following summer to Hartford, Connecticut, to improve and exhibit his boat. Finally, in 1797 he went to Bordentown, New Jersey (a stop on Fitch’s failed Philadelphia to Trenton passenger service), because it was “sickly in New York,” and built a boat employing two side - mounted paddle wheels. At this point, Morey considered his boat ready for commercial use and sought financial backers.

For reasons that are unclear, his backing fell through because of “a series of misfortunes”. This is likely the end of Morey’s direct work with steamboats – although there are many tales of a later fourth steamboat – but not the end of his steam engine patents. In addition to one received in 1795 for improvements he made working on the steam engine in boat, he received patents for other applications and improvements in 1799, 1800, and 1803.

Despite Morey's success in building a working steamboat, credit for the first successful steamboat line goes to Robert Fulton and his financier, Chancellor Robert Livingston. This was a cause for contention, as Morey claims that they took some of his ideas. His account, which seems more reasonable than later, derived accounts, is laid out in his letter to Duer and is as follows. The summer after the one Morey spent at Hartford, he returned to New York and gave Livingston a ride in his boat (perhaps at the advice of Benjamin Silliman — the publisher of Morey's papers — who knew Livingston to be a supporter of the arts ). He was impressed and offered Morey a “considerable sum” if he could improve the boat’s speed to 8 miles per hour. He also offered $7,000 for the rights to use his current work around New York but Morey declined the offer. However, he continued working towards Livingston’s speed goal. Morey also had conversations with Fulton and Livingston, and Livingston even traveled to Orford to see him (although Morey doesn’t say when or what was discussed). Later, Morey was on Fulton’s boat with Fulton, and he expressed his displeasure that his ideas had netted Fulton much but nothing for himself.

In 1815, Morey patented a “revolving” steam engine, described at length in the American Journal of Science in 1819 by John Sullivan, its purchaser. With the exception of one harsh initial review predicting that it would barely work – which was rebuffed by Sullivan, it was apparently well received and Sullivan’s description appeared in the Edinburgh Philosophical Journal along with an introduction praising American steam engine and boat refinements. Instead of a stationary cylinder driving a rod that turns a wheel through a second linkage, it seems that the cylinder is allowed to pivot as the rod moves, which then turns a crank. The cylinder’s pivot doubles as a valve that controls the direction and flow of steam according to its position. The claimed advantages of this configuration are lightweight, high - speed operation, durable construction, and low cost. This engine met with some commercial success; recorded applications include tugboats, a glass factory, and a sawmill in the Boston naval yard. One tugboat even sailed to South Carolina, where its owner was pleased by its performance. Morey received one more steam patent in 1817 but his interest had been captured by experiments with flammable vapors, which had started some time before.

In an 1834 letter to Professor Benjamin Silliman Morey writes, “It is now more than twenty years since I have been in the constant, I may say daily practice of making experiments on the decomposition of water, by mixing with its vapor that of spirits of turpentine, and a great portion of atmospheric air.” This would seem to understate the scope of some research that led to such diverse discoveries as the liquid fueled internal combustion engine, a method for carbonating water, and odd bubbles formed by molten resin. The last two appeared in journals in England and Germany, respectively.

Morey noted differences in flames near knots, perhaps rich in sap, or in wet wood. Eventually he experimented with anything he could find: “tar, rosin, rough turpentine, or the spirit, or alcohol, or any kind of oil, fat, or tallow; mineral coal, pitch - pine wood, and the knots, birch bark, pumpkin, sun - flower, flax, and other seeds; as well as many other substances.”

His experiments are described at length over several articles in the American Journal of Science and Arts. They are light on theory, and Silliman comments that “[Morey’s] results are often very valuable, and perhaps, in some cases, not the less so, for having been sought without the direction of preconceived, theoretical views.” This is mostly true; theory enters into these articles mostly for possible explanations. However, in 1834, 15 years after his first publication on the subject, he proposes a theory of combustion that has electricity as its basic force. Hints of this theory may be visible in his first paper, but his early experiments were not guided by it.

His first practical application was to heat water for his revolving engine. He observed that passing steam over burning coal or tar caused the flames to burn brighter and without smoke, and he theorized that the steam was decomposed in this process. Word of these experiments reached the eminent French chemist Gay - Lussac, and he commented on them in Annales de Chimie et de Physique in 1819. He contended that the temperature was insufficient to cause decomposition. Instead, the steam freed more flammable vapors in the fuel causing the flame’s change.

It turns out that Morey was correct. He produced what is now known as town gas. The oxygen from the water combines with carbon from the fuel to form carbon monoxide and the hydrogen forms a diatomic molecule. Both later burn to form water and carbon dioxide. Morey was not the first to use water - gas for lighting, and his devices, including the patented 1818 American Water Burner, simply used the gas immediately instead of piping it to be burnt elsewhere, done as early as 1792 in England. It seems that Morey did not know of this advance or at least did not recognize it as the same process. Strangely, in 1819 J.F. Dana of Dartmouth and Harvard proposed attaching steam boilers to street lamps to take advantage of Morey’s discovery, but water - gas was already being piped to some London street lamps from a central source in 1812. Still, Morey’s device did produce more light, and there is evidence that it resulted in more efficient combustion.

During his experiments, Morey discovered that the vapor of turpentine, when mixed with air, was explosive. He recognized its potential, developed an engine, and wrote an unpublished description in 1824, which he modified in 1825 and 1826. He finally published and patented the later in that year. The revisions between the drafts are small, and deal mostly with reworking of the engine’s valves.

The engine has much in common with modern ones. It has two cylinders, a carburetor, a familiar arrangement of valves and cams. However, unlike modern engines, and unlike the earlier 1807 François Isaac de Rivaz engine, the explosion did not directly provide power. Instead, the explosion expelled air from the cylinder through a one - way valve. The cylinder was cooled by a water jacket and water injected into the combustion chamber after it fired. The cooling gasses caused a vacuum and atmospheric pressure drove the piston. Morey did mention trying direct action, and elaborated on it in other descriptions. However, his method was more complicated and possibly less efficient because it used more of the engine’s stroke to draw in fuel.

Morey demonstrated his engine in New York and Philadelphia and there are eyewitness reports for both. In Philadelphia, he demonstrated it powering a boat and a wagon. Unfortunately, when he decided to demonstrate the car on the street, he fell off after starting the engine and the vehicle powered across Market Street into a ditch. This was the second car ride in the world, and the first in the United States. Despite these mostly successful demonstrations, Morey could not find a buyer, and became frustrated. A letter from Reverend Dana of Orford written in October 1829 tells of Morey’s trip to Baltimore, “I am told, the Capt. Is determined to make one more vigorous effort, to sell his patent right for some of his modern inventions [he later singles out the vapor engine], and if he does not now succeed, he will give the matter up, and return to Orford, to spend his days in quiet.” Morey did not find a buyer, and as he was then in his late 60s, it made sense to stop traveling up and down the east coast and call it quits.

While the engine was state of the art, it was not novel in many respects. Morey seemed aware of contemporary internal combustion work – Hardenberg, who wrote a book on Morey’s engine, adeptly noted that in his 1825 draft Morey “stated that he named his invention ‘vapor engine, to distinguish it from the… gas engine.’” However, Hardenberg concludes that Morey could only have known of three engines similar to his. He never mentioned them, and Hardenberg concludes that they did not influence Morey. His internal combustion engine is the first documented in the United States, and his use of liquid fuel and a heated surface carburetor was world's first. Another interesting feature was the wire mesh used to prevent the combustion from reaching the carburetor. This feature was reinvented and patented again in 1872 because the patent office had lost Morey’s patent in the 1836 patent office fire.

The lack of interest in his vapor engine is unfortunate, because the vapor engine was his most farsighted invention. Morey notes in his unpublished 1824 draft that:

He mentions "the earth's surface" because elsewhere he proposed using the engine to propel balloons.

Now that the internal combustion engine’s potential has been realized, people often focus on his engine. The first push to popularize his work was done by Charles Duryea, a fellow inventor who produced the first gasoline engine in America around 1890. He funded the creation of two working replicas of Morey’s Engine — one is in the possession of the Smithsonian and the other is owned by Dean Kamen — and wrote about how Morey’s engine was a direct precursor of the modern engine. He overstates Morey’s influence, which unfortunately is nearly nonexistent. Still the popularization of Morey’s work continues. Recently, this task has been taken up by people other than locals and engineers – including comedian Jay Leno – an avid car collector.

In 2004 10 of Morey's patents, including the one for the internal combustion engine, were "found" in the Dartmouth College archives. In truth, they had never really been lost; they were previously in his family's possession and many researchers had accessed them. However, they have now been scanned and available from the patent office's website.