In 1994, computer scientists Graeme Ritchie and Kim Binsted designed a computer program to generate original riddles:

• What do you call a ferocious nude? A grizzly bare.
• What do you get when you cross breakfast food with a murderer? A cereal killer.
• What’s the difference between leaves and a car? One you brush and rake, the other you rush and brake.
• What’s the difference between a pretty glove and a silent cat? One is a cute mitten and the other is a mute kitten.

They called it JAPE, for Joke Analysis and Production Engine. In 1997 they convened a group of 8- to 11-year-old children to act as judges and presented them with a random selection of JAPE-produced riddles, human-produced riddles, nonsense nonjokes, and sensible nonjokes. Then they asked them to decide whether each text was a joke and, if so, how funny it was and whether they had heard it before.

“The results showed that the JAPE-produced riddles were identified as jokes just as reliably as the human-produced ones, and both were easily distinguished from the non-jokes,” writes Rod Martin in The Psychology of Humor (2007). “Although the JAPE-produced jokes were rated as less funny, on average, than the human-produced jokes, a number of the JAPE riddles were rated as being just as funny as those produced by humans.”

(Binsted, K., Pain, H., & Ritchie, G., “Children’s Evaluation of Computer-Generated Punning Riddles,” Pragmatics and Cognition, 5(2) [1997], 309-358.)

Writing fables is harder.

If a “dog year” is equivalent to seven human years, then time passes seven times more quickly for dogs than for humans. So in 1990 Rodney Metts invented a novelty watch that reflects this by advancing at seven times normal speed. This is a reminder as much to you as to your pet:

If a dog is kept locked in the basement of a house during an eight or nine hour day, for example, while its owner is away, the elapsed time on the dog watch will be 56 to 63 hours, or approximately two and one-half days. A one-hour ride in an automobile will register seven hours on a dog watch. Thus the value in dog time of a human activity will become quickly apparent.

That’s the actual patent figure. Part 10 is “dog.”

For the conservation-minded, in 1988 Joseph Beck patented a “sail attachment” for a bicycle. The mast extends upward from the rear wheel, and it’s mounted on a pivot so that it will swing out of the way if you run into something. I’m not sure how you’d store it, though.

Related: In 1826 George Pocock invented a buggy drawn by kites.

Patented in 1993, Raymond Norris’ “combined camouflage and decoy device” is pretty straightforward: You wear a cap that supports an artificial head (to attract birds) and a cape (to hide you from them).

Just hope it doesn’t attract giant geese.

Patented in 1914, Socrates Scholfield’s “illustrative educational device” uses two spiral springs to demonstrate the existence of God. Or to demonstrate the tension between good and evil. Or to demonstrate the consciousness of an animal organism. Actually I’m not sure what it demonstrates, and I’ve read the five-page abstract twice.

This schematic device … provides an educational emblem of the conscious relation that must exist between the co-extensive dispensing mediums for beneficence and maleficence, in the terrestrial factory; and it clearly indicates that the attribute of maleficence, which is ascribed to the realm of the adverse medium, may, under certain changed conditions, be made subject to decrease, and to a change in its relative action; while the attribute of beneficence, which pertains to the realm of the controlling supreme governor, is unconditioned, unchangeable and everlasting.

Here’s the whole thing if you want to try it out. Be careful, I guess.

Visitors to Arizona’s Maricopa County Fair saw a surprising demonstration in 1884 — local inventor Lucius Copeland had added a steam engine to a bicycle to create a new vehicle that could travel 15 miles in an hour.

He sought funding for his idea but couldn’t summon enough public interest. It’s now recognized as one of the first motorcycles.

Peter Krovina’s “sailing system,” patented in 1981, replaces a conventional sail with an adjustable windmill — while it’s driving the boat forward, it’s also storing power in batteries.

The batteries serve the boat’s need for electricity, powering the running lights, the cabin lights, space heaters, and the cooking stove.

Best of all, they eliminate the need for an engine — an electric motor drives the screw.

This is admirably simple: In 1876 Ethelbert Watts invented a portmanteau that doubles as a bathtub:

“The object of my invention is to provide a portmanteau, valise, traveling-bag, or other equivalent article used for the transportation of clothing, which shall be convertible into a bath-tub, so as to afford travelers in places where such conveniences are wanting the luxury or comfort of bodily ablution.

“Articles of clothing, &c., may be packed and carried in it as in any portmanteau or equivalent device. When it is desired to use it as a bath-tub the portmanteau is opened, as shown in Fig. 1, and the contents removed. Water is then poured in, when a bath may be enjoyed, as in a permanent tub or fixture. When the bath is over, the water is poured or dipped out, the interior dried by any suitable means, and the device is again ready for use as a portmanteau.”