POLTTECENIC ASSOCIATION PROCEEDINGS. $93 



A very interesting discussion on the value of this method of 

 cutting off steam, followed the reading of the foregoing paper; 

 after which the meeting adjourned. 



October 3, 1867. 



Prof. S. D. Tillman in the chair; J. Wtatt Rbid, Esq., Secretary. 



The Chairman opened the meeting by reading the following items 

 of scientific news: 



NEBULA. 



Prof. W. A. Miller, in a lecture before the Royal Institution of 

 Great Britain, on spectrum analysis, after describing the charac- 

 teristics of the fixed stars revealed by the spectroscope, passed to 

 another series of objects which have long been enveloped in mys- 

 tery. Scattered over different parts of the heavens are a number 

 of remarkable bodies, which look like patches of light or luminousj 

 clouds. In some cases they are collected into rings; in others, into 

 spirals; while in other instances they assume still more definite 

 forms. These nebulous masses of light have, ever since their dis- 

 covery, excited in a high degree the wonder and curiosity of those 

 who have examined them. The interest they awaken is perhaps 

 still further increased by a remarkable speculation concerning 

 them, put forth by Sir William Herschel, when asked if it was not 

 possible that these nebulae might be the primordial forms of matter, 

 from which stars and suns and their attendant planets had been j)ro- 

 duced. Notwithstanding minute and careful observations by the 

 telescope, nothing was known of the physical condition of the mat- 

 ter composing these nebulae. It was not even known whether they 

 were aggregations of stars, so infinitely distant from us that we 

 could not discern the separate stars, or whether each nebulae was a 

 sepai'ate luminous object of a nature entirely different from the 

 stars. Mr. Huggins, has been enabled in several instances, to show 

 that the nebulae are not stars, but that they are composed of glow- 

 ing gas; and, further than that, he has been enabled to give some 

 hint as to what this gas may be. When he was examining one of 

 these nebulae with his spectroscope, for the first time he observed 

 what appeared to be a single vertical line of light; this, on closer 

 inspection, was seen to be accompanied by two fainter lines in the 

 more refrangible portion. This observation immediately gave him 



