I know "patent troll" is a pretty loaded, derogatory term for such an esteemed man, but I think it fits, at least in this one particular instance. Here's what's going on:
After a number of difficult attempts to commercialize his improved steam engines, Watt had formed a company with Matthew Boulton that finally brought him his well-deserved success. You can sort of think of Boulton as the Steve Jobs to Watt's Steve Wozniak. Sort of. Anyway, by the later 1700s, the Boulton and Watt Steam Engine Company was cranking out stationary steam powerplants for factories, mines, and probably at least one depraved monarch's state-of-the-art sex dungeon.
The company had a number of notable employees and partners, including William Murdoch. Murdoch was a gifted young engineer, and like so many of us, what Murdoch really wanted was a car. Murdoch had heard about Cugnot's cumbersome Steam Dray of 1769, and realized that the concept was sound, but the design and execution could be much better. By 1784, Murdoch had a working model.
A colleague working near Murdoch in Cornwall wrote to Watt of Murdoch's research into steam vehicles, saying
It is no less than drawing carriages upon the road with steam engines...he says that what he proposes, is different from anything you ever thought of, and that he is positively certain of its answering and that there is a great deal of money to be made by it.
... which is especially fascinating because it shows just how early the economic potential of automobiles was considered. Watt, however, wasn't impressed, and was generally against the idea of steam engines being used for transportation. Watt never built high-pressure steam engines, which he rightly assumed would eventually be necessary for automobiles, and always felt they would be inherently unsafe.
Watt also wanted Murdoch working on Boulton and Watt projects, not his own crazy steam hot rods, and so had a vested interest in not encouraging this line of work.
Boulton himself reported back to Watt about Murdoch's work, saying
I verely believe he would sooner give up all his cornish business & interest than be deprived of carrying the thing into execution.
... and then went to far as to suggest to Watt that he should include steam carriages in his patent application. Now, Watt wasn't interested in making steam carriages. In fact, he himself understood just what taking out a patent on something he had no intent of making would be, writing back Boulton to say
I have given such descriptions of engines for wheel carriages as I could do in the time and space I could allow myself; but it is very defective and can only serve to keep other people from similar patents.
So, at the request and encouragement of his partner, Watt became one of history's first patent trolls. I say this because one of the accepted definition of a patent troll is an organization or individual who "Enforces patents against purported infringers without itself intending to manufacture the patented product or supply the patented service," or, in more detail,
The law states that a patent secures a right of the patentee to exclude others from using, making, selling, or importing the patented invention (35 CFR §271). The emphasis is on others. It is inconsequential in the eyes of the law whether or not the inventor practices the patented invention. To tie injunctive relief to the practice of an invention has no basis in law.
The whole goal of this patent was to keep steam vehicles from being created or sold, at least not without a fight. This didn't really stop Murdoch, who continued work on his working model, which people report having seen driving around Murdoch's living room. This also makes it Britain's very first self-propelled vehicle of any sort, ever.
He seems to have made at least one other larger (the exact size isn't known, and some believe a full-size, human-drivable version was built) fully-working model, and was taking steps to secure a patent. On a trip to London to get his steam carriage patented, Murdoch was intercepted by Boulton, who describes the incident in a letter to Watt:
He said He was going to London to get Men but I soon found he was going there with his Steam Carg to shew it & to take out a patent. He having been told by Mr W. Wilkn what Sadler had said & he had likewise read in the news paper Simmingtons puff which had rekindled all Wms fire & impations to make Steam Carriages. However, I prevailed upon him readily to return to Cornwall by the next days diligence & he accordingly arivd here this day at noon, since which he hath unpacked his Carg & made Travil a Mile or two in Rivers's great room in a Circle making it carry the fire Shovel, poker & tongs. I think it is fortunate that I met him, as I am persuaded I can either cure him of the disorder or turn evil to good. At least I shall prevent a mischief that would have been the consequence of his journey to London.
So, Boulton finds Murdoch with his model automobile, and smooth-talks him out of seeking a patent, despite being absolutely aware that the carriage did, in fact, work. He even consider's Murdoch's enthusiasm for building cars "a disorder."
Later, Watt and Boulton make sure to keep Murdoch busy with other jobs to keep his mind and resources away from becoming one of the first builders of cars. Jerks.
It wasn't just Murdoch that got pressured to stay out of the automobile business by Watt. Watt's correspondence reveals similar predatory practices to other inventors, in this case a London linen-draper named Moore:
If linendraper Moore does not use my engine to drive his chaises, he can't drive them by steam. If he does I will stop him. I suppose by the rapidity of his progress and puffing, he is too volatile to be dangerous.
Damn, James. Volume 32 of the Antiquary from 1896 sums it up well, saying
The letter gives the key to Watt's position in the matter. He had no faith in the feasibility of steam locomotion on common roads, but in spite of that wished to retain the field all to himself.
Now, I have tons of respect for James Watt, but it's hard not to think the man's a jerk when he takes such lengths to keep everyone else from playing in a game he doesn't even want to play himself.
As a result of Watt and Boulton's efforts, Murdoch's simple and cleverly designed steam carriage (which was also the first transportation application of the crankshaft) never got the further development it deserved, and its greatest achievement was spooking the hell out of a clergyman who saw the carriage chugging down the street in front of a running Murdoch. The poor vicar was sure he'd just seen a devil.
Who knows how much more rapidly early steam automobile technology would have progressed If Watt had been less pessimistic and greedy? Perhaps we'd have had E-Types breaking down in languid splendor by 1910, and today perhaps the British motor industry would still be the force it once was.
We'll never know for sure, but regardless I'll take this moment to give the brilliant reputation of James Watt a little bit of tarnish. Thanks a lot, troll.