Remember the schoolyard riddle, "Why do firemen wear red suspenders?" To hold their pants up, right? Maybe.

An American inventor once applied for a patent for a pair of suspenders that he said could also be used to aid one in safely escaping a burning building. Attach one end of the suspenders to a secure object in the building, the other to your pants, then jump. The elasticity breaks the fall.Well, it sounds more reliable than another inventor's fire escape kit: a pair of jump shoes with thick crepe soles and a small hat with a parachute affixed to the top of it ("not recommended above the second floor").

Don't get Robert Richardson started talking about inventions. The Bettendorf, Iowa, retiree spent his career as a Patent Office examiner and, for 35 years, has been a patent attorney.

The U.S. Patent Office is approached the point, Richarson said, when last month it issued its 5,000,000th patent.

Five million. That includes at least 3,500 attempts to build a better mousetrap (among them guillotines and electrocution devices) and at least one attempt to build a better tapeworm trap.

"A small baited trap is attached to a string," Richardson recalls of that patent. The tapeworm sufferer swallows the trap, holds onto the string and waits.

"I suppose they feel a little silly," he continued, "walking around with a piece of string hanging out of their mouth."

Over the years, Richardson saved copies of the more bizarre and offbeat patent applications handled by the U.S. Patent Office. Recently, he decided to try to pique the interest of a publishing house.

"I gathered about 500 patents together and sent them to Sterling Publishing," he said. "They weighed about 16 pounds."

The result has become "The Weird & Wondrous World of Patents."

Some of the inventions and their accompanying first drawings are curious because of their place in history: R.J. Gatling's machine gun, Alfred Nobel's dynamite, Enrico Fermi's nuclear fission reactor, the paper clip and the pay telephone.

Richardson has a little story to tell about each patent that caught his eye.

"Ivory, the floating soap," he explained, "was invented when a worker at Procter & Gamble forgot to turn off the soap mixer when he went to lunch." By the time the worker returned, the soap mix was full of air bubbles, and the bars poured from it floated.

The next time you pop something in the microwave oven, thank the Raytheon Co. factory worker who, in 1940, noticed that each time he was exposed to microwaves they melted the candy bars in his pockets.

Sorting through the Patent Office's archives, Richardson found the following:

- Three patents for escapable coffins and another for a vertical casket to help maximize conservation of cemetery space.

- A 1908 invention for "sexual armor," a metal-plated unisex chastity belt designed to thwart self-abuse in adolescence and thus lower the national rate of "insanity and feeble-mindedness."

- A 1930 patent for a car-mounted megaphone that permits drivers to be heard when they swear at the car in front of them.

- More practical than the bedpost, a chewing gum locket for keeping the used Wrigley overnight.

- A device, designed to thwart bicycle theft, that sends a needle upthrough the rider's seat if not properly disarmed by the owner.

- A self-tipping hat, a hat theft alarm and an air-conditioned hat.

- A dimple-maker.

- A "birthing spinnet" that uses centrifugal force to aid in child delivery.

- An alarm clock that squirts water in the sleeper's face.

- A cigarette pack that emits a coughing noise when it is picked up.

- A pair of shoes with heels and toes reversed, so that anyone trying to track the wearer will not know if his prey is coming or going.

- A shoulder harness, from which a horse stirrup is suspended on each side of the wearer, purported to aid in the facilitation of sexual congress.