The limit will probably be reached by the spectrograph of the Yerkes Observatory, which is now being put into operation by Professors Hale and Frost.
The Mills spectrograph of the Lick Observatory in the hands of Professor Campbell has, notwithstanding these difficulties, yielded results of extraordinary precision.
Campbell finds with the Mills spectrograph attached to the great 36-inch telescope of the Lick Observatory that Mira is receding from the earth at the apparently constant velocity of about 38 miles a second.
Later and more precise work with the mass-spectrograph showed that the discrepancy had at first been much over-estimated.
The spectrograph of the Observatory was also employed in observations of stars, and again led to unexpected discoveries.
More recently a slight discrepancy between determinations of the atomic weight of hydrogen by the mass-spectrograph and by chemical means led to a successful search for a heavy isotype of hydrogen.
Its spectrograph is massive in construction, and by extending deep into the earth, it enjoys the stability and constancy of temperature required for the most exacting work.
When this nebula is observed with a slitless spectrograph the hydrogen and nebulium components are seen as circular discs, but the hydrogen discs are larger than the nebulium discs.
Slipher's recent work with a spectrograph seems to show that the dozen spirals observed by him are moving with high speeds of approach and recession; from 300 km.
The explanation is simple: in the Class B doubles the components are close together, their orbital velocities are very high and change rapidly, and the spectrograph is able to discover the variations with little loss of time.
Mounting of the Mills spectrograph at the Lick Observatory.
I don't know how successfully we can get a spectrograph of the comet, but it's worth an attempt.
Maybe we can use their new mass spectrograph to help analyze whatever we collect.
If we took a spectrograph of the comet and found this same line strongly present, we would have a good case for proving the comet was the source of this substance.
