from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An instrument used to observe solar radiation directly.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An instrument used for observing solar radiation.
spectro- + helioscope (Wiktionary)
He later built a spectrohelioscope, one of two in Britain, used for solar observation in the elemental light bands of the spectrum, which directed the sun's light through a succession of mirrors into his observatory in the basement of his house.