William Carr’s “improved burglar-trap,” patented in 1868, is a man-size version of a no-kill mousetrap. The unwitting burglar steps on the trapdoor and falls into the chamber, where his own weight on the false bottom pulls the doors shut again.

“It will be seen that the catches II II’ and I I act, in connection with the weight of the person upon the platform, in retaining the doors in their closed condition, and, even in case the prisoner should succeed in scaling the walls of the chamber, the locking-devices H H’ and I I’ will effectually prevent him forcing open the trap-doors.”

During the day the proprietor can pull a cord to engage the catches by hand, to prevent his customers from falling in themselves.

Indoor ski slopes tend to be short because they’re expensive to build. In 1986 Nobuyuki Matsui proposed a space-saving solution: Arrange the slope in a helix or a figure eight around a support tower that contains an elevator. Skiers can ride to the top and enjoy a long continuous run back to the bottom. To reduce cooling costs, the whole thing can be built underground (with a ski lodge at the top) and all the snow-making accomplished within a special enclosure that works its way down the slope.

“In order to simulate actual outdoor skiing conditions, provisions are made to vary the steepness of the slope from place to place. In addition, facilities are provided to produce random simulated moguls or an entire mogul field. Thus, during one run of the slope, most, if not all, of the conditions encountered on natural outdoor slopes may be simulated and incorporated into the run.”

“Even if the propeller had the power of propelling a vessel, it would be found altogether useless in practice, because the power being applied in the stern it would be absolutely impossible to make the vessel steer.” — Sir William Symonds, Surveyor of the Royal Navy, 1837

In 1988 Martine Tischer proposed a novel way to add interest to a gift: wrap it in sheets of uncut U.S. currency:

First of all, currency, particularly U.S. paper currency having the color green, is very attractive and suggests power and wealth … If desired, the package can be framed. Also if desired, the recipient of the package can deposit the whole sheet in a bank or exchange it at a bank for cut bills. The wrapping itself can be used as a medium of exchange, since it is money.

See Gotcha.

Rayma Rich’s “collapsible riding companion,” patented in 1991, offers female travelers an inventive way to deter criminals: Set up the false head and torso in your passenger seat, dress it in a suitable shirt, and you have a devoted male escort who will accompany you anywhere and never ask for overtime.

When you get back to the airport, disconnect the head, stow it in the torso, and “the riding companion becomes a lightweight, easy-to-carry rectanglar case for traveling.”

Patented in 1992 by Celess Antoine. Some things don’t need a lot of explaining.

If you live in an arid climate there’s an alternate solution.