he·li·o·stat 
(hēlē-ə-stăt′)
(hēlē-ə-stăt′)n.
An instrument in which a mirror is automatically moved so that it reflects sunlight in a constant direction. It is used with a pyrheliometer to make continuous measurements of solar radiation.
- marginate
- margination
- margined
- marginocephalian
- Margot
- margravate
- margrave
- margravial
- margraviate
- margravine
- Margrethe II
- Marguerite
- Marguerite
- marguerite
- Marguerite de Navarre
- Marguerite de Navarre
- Marguerite de Valois
- Marguerite de Valois
- Marguerite Donnadieu.
- Marguerite Johnson.
- (Marguerite) Radclyffe
- Margulis
- Maria
- Maria
- Maria