| SPECTRA allows visitors
to be detectives, examining the fingerprints of elements
in the form of spectra. The exhibit provides gas-filled tubes of
Argon, Mercury vapor, Neon, Nitrogen, Helium and Xenon. As the user
turns the exhibit's pointer, a different element lights up. The
emission spectra of the various gases may be examined by selecting
a particular gas and viewing it through a diffraction grating. Spectra
of other sources of lighting around the museum can also be examined.