I know Charles Darwin is the Darwin that gets most of the press (well, except maybe for that dolphin that was in that underwater Star Trek show), but I think we need to take a moment to appreciate his grandfather, Erasmus Darwin: poet, physician, inventor, and, yes, possibly one of the world’s first gearheads. The man designed a car in 1764, and we have the drawings to prove it.
The first full-sized self-propelled machine that we can consider an automobile was Nicolas-Joseph Cugnot’s Steam Drag of 1769. Before that, there was Ferdinand Verbiest’s small model steam-turbine automobile in 1672. And before that, there was really almost nothing we could actually call an automobile—not even some of DaVinci’s clockwork-cart ideas.
In between the toy steam carriage and Cugnot’s not-exactly-successful full-sized self-propelled vehicle there is another automobile. Well, the design for an automobile, at least, and even if it wasn’t ever actually built, it’s significant because it’s the first serious attempt to design a passenger-carrying motorized, self-propelled vehicle.
That vehicle is Erasmus Darwin’s Fiery Chariot.
In a 1764 letter to Matthew Boulton, Darwin describes and draws the design of a fascinating steam-powered carriage. Keep in mind that this is still five years before Cugnot would unveil his lumbering Steam Drag, and the steam engine itself had only really been in common use for about 50 years. A steam engine that operated at anything above atmospheric pressure wouldn’t be around until 1781. Believe me, 1764 is a very early time to even be imagining cars.
The full text of the letter is here, but we’ll pick out some highlights. First, I like his general list of what his fire-carriage should do:
These things are required. First a Rotatory Motion. 2 easyly altering its Direction to any other Direction. 3 To be accelerated, retarded, destroy’d, revived instantly and easyly. 4 the Bulk, Weight, and Expence of the machine as small as possible in proportion to its Use.
Rotary motion into progress in a chosen direction, and ease of changing direction; speeding up, slowing down, starting stopping; making sure it’s a reasonable size. These are all things we want in cars to this day. Erasmus was right on the money there.
He has a bit of a debate with himself as to whether three or four wheels would be best, and after some discussion as to which wheel or wheels should get the power (remember, nobody had really done anything like this before) he decides that a three-wheeled setup with at least one driven wheel:
Hence I conclude that a three wheel’d Carriage is the best, that to move any one of those wheels, will answer as well as moving the first wheel or nearly so. And that two wheels can not be moved in any Carriage without great Friction in turning about.
(For some reason, this book suggests he decided on four wheels; I’m not sure why, the scans of the letter seem pretty clear about his tricycle decision.)
This is sensible when you consider how much easier it is to build a one-wheeled steering mechanism, but a little puzzling when you consider Darwin specifically. That’s because, back in 1758, Darwin had designed a carriage steering mechanism that is essentially just like the Ackermann steering geometry that is used (in some form) by almost every modern car.
Amazingly, in 1758 Darwin was traveling nearly 10,000 miles a year—pretty much what a modern American drives. He installed his improved steering geometry setup on two carriages, which he tested over 20,000 miles. It never really caught on because it was just more complex and expensive to build than a simple steering pivot in a carriage, but it would become common decades later.
Really, just figuring out this sort of steering mechanism already makes him an unsung hero of motoring, if you ask me.
Yes, it’s a little weird he’d just abandon his improved steering idea for his Fiery Chariot, but I guess he was more concerned with the propulsion and just wanted to keep things simple.
Speaking of propulsion, Darwin describes the engine for us – it’s sort of a steam opposed-twin:
Let there be two Cylinders, antagonists, at each End of the Beam, or Lever as it is call’d, which may be made of a Bar of Iron, the diameters of the Cylinders equall. And each equal…Inches. One Steam Cystern serves both, and is placed between them. NB. the agitation of the Water by the roughness of the roads will encrease the Quantity of Steam.
He’s roughly describing a twin-cylinder steam engine of the era. He also describes a bit how the engine would be sped up or slowed down:
Hence by the management of the steam Cocks the Motion may be accelerated, retarded, destroy’d, revived, instantly and easily. And if this answers in Practise as it does in theory, the Machine can not fail of Success! Eureka!
The Cocks of cold water may be moved by the great work, but the Steem-Cocks must be managed by the Hand of the Charioteer, who also directs the Rudder-wheel.
That’s an interesting part, because he refers to the driver as a “Charioteer,” and, in addition to steering the car, the Charioteer would be managing the steam and cold water cocks that either speed up or slow down the rotation of the steam engine. This means he’s thinking about the fiery chariot as being something one person would pilot, which makes this in some ways a more advanced design than the steam automobiles of the early-to-mid 1800s, and more like modern cars.
Now, the way he handles the power to the drive wheels is incredibly interesting. There’s no real flywheel here, and the power is transmitted via the direct back-and-forth movements of the piston rods. To power both wheels, each wheel is connected to one cylinder’s piston-rod. He designs a very clever transmission system to allow for each axle to be powered independently while the other axle and wheel freewheels and prepares for the next stroke:
e f g h, is a Roller, and a rachet-wheel like those on which the Cord of a Jack is wound upon. AB are the axis of the two hinder wheels of the fiery Chariot, upon which axis also the Rollers move, when these Rollers move forwards, the Teeth of the Rachets ef and mn, reciprocally carry their neighbouring wheel. Let the arm ab be now elevated, and moves the wheel A forwards, and at the same Time by turning the ingenious wheel with contrart Teeth gh, winds up the Chain upon the roller h.l.m.n. The wheel B all this Time not being acted upon. Then when cd is again elevated the Chain is wound round efgh as at present.
NB. the curves ab and cd are not parts of Circles, the yare design’d to vary from circles in order to wrap, and unwrap the Chains on the Rollers, nor will this little deviation from a regular force, by varying the arm of the lever, be at all felt, or may be counteracted by the form of the Roller, on which the Chain wraps. – The contrat wheel gh ought to have been under the Rollers, so that it may be out of the way of the Boyler. The upper surface of the Carriage is in this Form.
It’s sort of tricky to picture, but it’s something like this: when the piston rod is having its equivalent of a power stroke, a cord around one of the half-shafts would be unwound, moving the wheel. The other half shaft would have its wheel free-wheeling while the shaft counter-rotated via the universal gear below, winding up its cord for the next power stroke from the piston.
It’s an odd and clever solution, and possibly one of the first—likely the first —automobile transmission designs ever. Interestingly, it’s also sort of taking the place of the crankshaft on a conventional car engine, converting the reciprocating motion into rotational motion.
The letter wraps up with a request that his Boulton check out how much coal and water steam-powered fire engines use (remember these engines were used just for pumping, not locomotion) so he could get an idea of how much water and coal his fiery chariot would need to carry:
If you could learn the Expence of Coals to a common Fire-engine, and the Weight of Water it draws, some certain Estimate may be made if such a Scheme as this would answer. Pray don’t shew Wyot this Scheme, for if you think it feasible, and will send me a Critique upon it, I will certainly if I can get somebody to bear half the Expense with me, endeavour to build a Fiery Chariot [and?] if it answers get a Patent. If you chuse to be Partner with me in the Profit, and Ex[pense] and Trouble, let me know: as I am deter[mined?] to execute it, if you approve of it.
I’m pretty sure “Wyot” is a way of spelling “Watt” as in James Watt, one of the people who made steam power really practical. Watt was in business with Matthew Boulton, so it makes sense Darwin would need to counsel Boulton to keep the letter and the steam carriage plan secret.
Darwin knew Watt, and Watt was aware of the possibilities of making steam-powered vehicles– in fact, Watt went so far as to take a patent out on steam vehicles, but only because he didn’t want anyone to build them at all. He was sort of a patent troll.