Latest By
Category:
Armor
Artificial
Intelligence
Biology
Clothing
Communication
Computers
Culture
Data Storage
Displays
Engineering
Entertainment
Food
Input Devices
Lifestyle
Living Space
Manufacturing
Material
Media
Medical
Miscellaneous
Robotics
Security
Space Tech
Spacecraft
Surveillance
Transportation
Travel
Vehicle
Virtual
Person
Warfare
Weapon
Work
"A good science fiction story should be able to predict not the automobile but the traffic jam."
- Frederik Pohl
 |
| Electrified Fence | ||
| A wire fence carrying an electrical charge sufficient to deter crossing the boundary. |
| Well, how have you arranged the fence?"
"I start twelve immensely strong wires--naked, not insulated --from a big dynamo in the cave--dynamo with no brushes except a positive and a negative one--" "Yes, that's right." "The wires go out from the cave and fence in a circle of level ground a hundred yards in diameter; they make twelve independent fences, ten feet apart--that is to say, twelve circles within circles--and their ends come into the cave again." "Right; go on." "The fences are fastened to heavy oaken posts only three feet apart, and these posts are sunk five feet in the ground." "That is good and strong." "Yes. The wires have no ground-connection outside of the cave. They go out from the positive brush of the dynamo; there is a ground-connection through the negative brush; the other ends of the wire return to the cave, and each is grounded independently." "No, no, that won't do!" "Why?" "It's too expensive--uses up force for nothing. You don't want any ground-connection except the one through the negative brush. The other end of every wire must be brought back into the cave and fastened independently, and _without_ any ground-connection. Now, then, observe the economy of it. A cavalry charge hurls itself against the fence; you are using no power, you are spending no money, for there is only one ground-connection till those horses come against the wire; the moment they touch it they form a connection with the negative brush _through the ground_, and drop dead. |
| From A Connecticut Yankee in King Arthur's Court,
by Mark Twain. Published by Not known in 1889 Additional resources -
|
Many sources credit Twain as the earliest source for this idea - but I think there is at least one earlier reference that should count.
In his 1875 epic 20,000 Leagues Under the Sea, Jules Verne writes about electrifying a stair rail or cable to prevent unwanted intrusions onto the Nautilus.
Comment/Join this discussion ( 2 ) | RSS/XML | Blog This |
Additional
resources:
More Ideas
and Technology from A Connecticut Yankee in King Arthur's Court
More Ideas
and Technology by Mark Twain
Tech news articles related to A Connecticut Yankee in King Arthur's Court
Tech news articles related to works by Mark Twain
| Flimmer Navy Drone Flies And Swims |
| Indian Court Says Brain Scan Proves Murder |
| Background Draw-a-Secret (BDAS) Makes Graphical Passwords |
| ID-U Biometrics Eye Tracking Signature |
Want to Contribute an
Item?
It's easy:
Get the name of the item, a
quote, the book's name and the author's name, and Add
it here.
| <Previous | Next> |
|
|
|
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
|
'Lucky touched the leap knob and the hopper's leg retracted.'
'It was among these leviathans that the little gyrocar was daring to thrust its puny self...'
'That sail will be twenty thousand miles at the wide part.'
'Out in the New Moon, just ask for what you want...'
'For long-distance calls the ratio of commercial to conversation was as high as 10 to 1...'
