Which makes no sense at all as a monkey is, in archaic naval parlance, a brass triangle which iron cannon balls are piled up inside of.

FORBES: Why Wind Power Doesn't Work

The iron triangle of employers, accountants and insurance providers has levelled health spending after years of steady growth.

ECONOMIST: Health care

Highly organized professional educators, sympathetic liberal legislators and a constituency of manipulable education consumers form a classic "iron triangle" that has proved impervious to reform.

FORBES: Are We Spending Too Much On Education?