magnetograph
noun
mag·ne·to·graph mag-ˈnē-tō-ˌgraf 
: an automatic instrument for recording measurements of a magnetic field (as of the earth or the sun)
Word History
First Known Use
1847, in the meaning defined above
- fourfold
- fourfolder
- fourfoldest
- fourgon
- fourgons
- Fourier
- Fourier analysis
- Fourier series
- Fourier transform
- Fourier's theorem
- Fourierism
- fourierisms
- fourierist
- Fourieristic
- fourierists
- fourling
- fourmarierite
- fourpence
- fourpence ha'penny
- fourpences
- fourpennier
- fourpennies
- fourpenniest
- fourpenny
- fourpenny nail