20 PHILOSOPHICAL TRANSACTIONS. [aNNO IJQl. 



It has been observed, on a former occasion, that all the smaller parts of other 

 great systems, such as the planets, their rings and satellites, the comets, and 

 such other bodies of the like nature as may belong to them, can never be per- 

 ceived by us, on account of the faintness of light reflected from small opaque ob- 

 jects : in the present remarks therefore, all these are to be entirely set aside. 



A well connected series of objects, such as mentioned above, has led us to in- 

 fer, that all nebulge consist of stars. This being admitted, we were authorized 

 to extend our analogical way of reasoning a little further. Many of the nebulae 

 had no other appearance than that whitish cloudiness, on the blue ground on 

 which they seemed to be projected ; and why the same cause should not be 

 asigned to explain the most extensive nebulosities, as well as those that amounted 

 only to a few minutes of a degree in size, did not appear. It could not be incon- 

 sistent to call up a telescopic milky way, at an immense distance, to account for 

 such phenomena ; and if any part of the nebulosity seemed detached from the 

 rest, or contained a visible star or two, the probability of seeing a few near stars, 

 apparently scattered over the far distant regions of myriads of sidereal collections, 

 rendered nebulous by their distance, would also clear up these singularities. 



In order to be more easily understood in his remarks on the comparative dis- 

 position of the heavenly bodies, Dr. H. mentions some of the particulars which 

 introduced the ideas of connection and disjunction : for these, being properly 

 founded on an examination of objects that may be reviewed at any time, will be 

 of considerable importance to the validity of what we may advance with regard to 

 the lately discovered nebulous stars. On June 27, 1786, he saw a beautiful 

 cluster of very small stars of various sizes, about 15' in diameter, and very rich 

 of stars. On viewing this object, it is impossible to withhold our assent to the 

 idea which occurs, that these stars are connected so far one with another as to be 

 gathered together, within a certain space, of little extent, when compared to the 

 vast expanse of the heavens. As this phenomenon has been repeatedly seen in a 

 thousand cases. Dr. H. thinks he may justly lay great stress on the idea of such 

 stars being connected. On Sept. g, 1779, he discovered a very small star near 

 I Bootis. The question here occurring, whether it had any connection with i or 

 not, was determined in the negative ; for, considering the number of stars scat- 

 tered in a variety of places, it is very far from being uncommon, that a star at a 

 great distance should happen to be nearly in a line drawn from the sun through c, 

 and thus constitute tlie observed double star. Sept. 7, 1782, when Dr. H. first 

 saw the planetary nebula near u Aquarii, he pronounced it to be a system whose 

 parts were connected together. Without entering into any kind of calculation, 

 it is evident, that a certain equal degree of light within a very small space, joined 

 to the particular shape this object presents to us, which is nearly round, and 

 even in its deviation consistent with regularity, being a little elliptical, ought 



