THtEJ- 
JOURNAL OF SCIENCE. 
APRIL, 1885. 
I. COMET SYSTEMS. 
By J. R. Sutton. 
says Guillemin, in his magnificent work 
| \ ‘The World of Comets,’ “in accordance with 
the fadts of Science, we endeavour to form an 
idea of the constitution of the visible universe, we see that 
the celestial bodies which compose this whole are every- 
where distributed into groups and associations united by the 
common bond of universal gravitation. 
“ There are the planetary systems. In the centre of each 
group is a star or central sun whose preponderating mass 
retains near him, circulating in regular orbits, other stars or 
planets, to which the central sun distributes heat and light. 
Our planetary system is the type of associations of this 
kind. 
“There are the stellar systems: groups of two, three, or 
more suns gravitating about one another, probably in ac- 
cordance with the same laws. 
“ In certain regions of the heavens the nebulae are them- 
selves to all appearance grouped into systems, so that the 
general plan of the universe is one vast synthesis of asso- 
ciations of different orders encompassing each other without 
end. Nor can any individual star escape the necessity of 
forming a part of one of these groups. 
“ Are these likewise systems of comets ?” 
In answer to this query M. Guillemin gives a resume of 
the results which followed upon the labours of Hock, a 
VOL. VII. (THIRD SERIES). R 
