Award of the Boyle Medal and Rep. of Sci. Com. R.D.S. 108 
the paper already referred to in this Report—“ On the Internal 
Motions of Gases compared with the Motions of Waves of Light” 
—he begins with a speculation, which little by little he brings 
nearer to verification in subsequent years. In this early paper 
he urges that definite wave-lengths in the spectrum of a gas 
involve periodic motions within the individual molecules, and that 
something like from 50,000 to 100,000 of such periodic and, 
probably, orbital motions must be executed between successive 
collisions in a gas, thus explaining why matter in the gaseous 
state can furnish a spectrum which consists of distinct lines. 
Independently of the suggestion of Maxwell, in 1873, Dr. Stoney, 
in 1874 (Belfast Meeting of the British Association, 1874, and 
Proceedings of the Royal Dublin Society, 1881), suggested the 
adoption of the Faraday molecular charge as a natural unit of 
electricity, more recently suggesting for it its present name of 
“Electron.” Somewhat before this period, in 1871, two papers 
appeared by him on “An Inquiry into the Causes of the Inter- 
rupted Spectra of Gases,” in the Philosophical Magazine, the 
last of the two being in conjunction with Professor EKmerson 
Reynolds, F.R.S. These deal with the sequences in the line 
spectrum of hydrogen and the absorption spectrum of chloro- 
chromic anhydride. In the spectrum of this vapour a significant 
relation was detected between the intensities of the lines of the 
spectrum and the succession of the intensities of the harmonics of 
a definite point on a violin string when set in motion by the 
bow. In 1891 he added to these ‘“‘ An Analysis of the Spectrum 
of Sodium” (Proce. Royal Dublin Society). Finally, in the 
earlier part of 1891, appeared his paper, “On the Cause of 
Double Lines and of Hqui-distant Satellites in the Spectra of 
Gases” (Trans. Royal Dublin Society). This is a summation 
and completion of his theory in its bearings on his previous 
work. 
According to Dr. Stoney the successive series of lines which he, 
and—following' in his footsteps—others, had determined in the 
spectra of gases, are referable to the motion of an electron within 
the molecule, or to an event following the same mathematical law. 
This motion gives rise to a definite series of elliptic partials, to 
each of which the motion of the electron may be referred and 
consequently the electro-magnetic disturbance represented by a 
