Oleg, please take a look at this site (there's even a picture):
http://www.ushistory.org/oddities/gibbet.htm

You'll have no doubts about the thing!
Here's an excerpt:

This is undoubtedly the city's most unique and macabre artifact. It's a human form made of iron bands designed to hold the body of an executed criminal for the purpose of public display. The devise -- more or less -- held the rotting corpse together for several weeks. The 18th century artifact at the Atwater Kent Museum is America's only complete gibbet. A partial gibbet survives in a museum in Salem, Mass. The primary meaning of the word "gibbet" is simply a gallows. The steel frame to display the culprit's body is properly called a "gibbet iron." But there are references to displaying the body as "gibbeting" and soon the steel frame, itself, was also called "a gibbet."

gibbet - an upright post with a projecting arm for hanging bodies of executed criminals in iron or chains - для устрашения публики

hooped - конструкция из металлических обручей, скрепленных выгнутыми прутьями

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Note added at 2001-12-14 20:27:00 (GMT)
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какую штуку - hooped frame? железная клетка, по форме и размерам напоминающая человеческое тело

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Note added at 2001-12-14 20:33:50 (GMT)
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а «gibbet» это и есть виселица (см. БАРС Гальперина)

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Note added at 2001-12-14 20:55:19 (GMT)
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м.б. сказать «виселица с клеткой»?

1. HOOP as a noun
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Main Entry: 1hoop
Pronunciation: 'hЁ№p also 'hup
Function: noun
Usage: often attributive
Etymology: Middle English, from Old English hOp; akin to Middle Dutch hoep ring, hoop
Date: 12th century
1 : a circular strip used especially for holding together the staves of containers or as a plaything
2 a : a circular figure or object : RING b : the rim of a basketball goal; broadly : the entire goal
3 : a circle or series of circles of flexible material used to expand a woman's skirt
4 : BASKETBALL -- usually used in plural
- hoopЎ¤like /-"lIk/ adjective
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2. HOOP as a verb
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Main Entry: 2hoop
Function: transitive verb
Date: 15th century
: to bind or fasten with or as if with a hoop
- hoopЎ¤er noun

So in your phrase the author should have put a ":" after 'gibbets' because he is then giving an explanation of the term:
соединенные железные конструкции/структуры (или можно в ед. числе) по размеру и форме человечесткого тела.

у меня явно не в порядке, а потому я даже забыла написать "в форме человеческого тела":

Невдалеке виднелась виселица, на перекладине которой болталась клетка из железных обручей в форме человеческого тела, предназначавшаяся для очередного висельника.

Повтор - специально для Хафизы:

The Gibbet
It's a human form made of iron bands designed to hold the body of an executed
criminal for the purpose of public display. The primary meaning of the word "gibbet" is simply a gallows.
http://www.ushistory.org/oddities/gibbet.htm