SOLAR MOTTOJ^. 281 



Mr. Messier in the year 1781, is. by the same iristru- Investigation 



ments, also proved to consist of stars : and thouffH they ^^ ^]^^ proper 

 • , , . . ,, J motion of the 



are seemingly compressed into a much smaller space, and 5^^. 



have also tlie appearance of smaller stars, we may fairly 

 presume that tlicse circumstances are only indications of 

 a greater distance, and that, being a globular cluster, 

 perfectly resembling the former, the distance being al- 

 lowed for, it is probably not less rich in the number of its 

 component stars. The distance of these two clusters from 

 each other is less than 12 degrees, and we are certain that 

 somewhere in the line joining these two groups there must 

 be a centre of gravitation, far superior in energy to the 

 single power of attraction that can be lodged in either of 

 the clusters. 



1 hare selected these two remarkable objects merely for 

 their situation, which is very near the line of the direction 

 of the solar motion ; but were it necessary to bring far- 

 ther proof of the existence of combined attractions, the 

 numerous objects of which I have given catalogues* 

 would amply furnish me with arguments. 



If a still more powerful but more diffused exertion of 

 attraction should be required than what may be found in 

 the union of clusters, we have hundreds of thousands of 

 stars, not to say millions, contained in very compressed 

 parts of the milky way, some of which have already been 

 pointed out in a former paper +. Many of these im- 

 mense regions may well occasion the sidereal motions we ^ 

 are required to account for; and a similarity in the di- 

 rection of these motions will want no illustration. 



With regard to the situation of the condensed parts of 

 the milky way, and of the two clusters that have been 

 mentioned, we must remark, that the seat of attraction 

 may be in any part of the heavens whatsoever; for 

 when projectile motions are given to bodies that are re- 

 tained by an attractive centre, they may have any direc- 

 tion, even that at right angles to its situation not 

 excepted. 



* Phil. Trans, for 1786, page 457; for 1789, page »i»; for 1801, 

 page 477- 



f Ibid, for 1 80a, psige 495. 



Vol. XV.— Dec. 1806. Pp It 



