the sky, known to us as nebulse, have been found from time to 

 time, as telescopes of increased powers have been brought to bear 

 upon them, to be mere star clusters ; hence it has been thought by 

 some that provided our telescopes had but sufficient power we 

 should be able to resolve all the nebulae in like manner into stars. 



Mr. Huggius was the first to made the grand discovery, that 

 the light of nebulse, unlike the light of the sun and stars, is not 

 composed of light of different refrangibilities, so that instead of 

 having a continuous spectrum crossed by dark lines, as in the case 

 of the sun and stars, the light from nebulae gives only a spectrum 

 of one or more bright lines, and this simple fact does away com- 

 pletely with the notion that nebulaj may be clusters of stars, and 

 shows them to be instead masses of glowing gas. 



Professor Frankland has lately demonstrated that the luminosity 

 of flame, as of a candle or coal gas, for instance, is not due, as has 

 hitherto been supposed, to minute particles of incandescent carbon, 

 but to the conversion of lighter vapours into heavier, by chemical 

 action or even by mechanical action, as by pressure ; therefore, the 

 mere fact of nebulae being luminous renders it highly probable 

 that condensation and combination are actually going on amongst 

 their component gases and vapours, and that consequently a nucleus 

 is being formed. 



Tlie spectroscope, besides telling us that nebulae are masses of gas, 

 indicates that two of the gases in question are hydrogen and 

 nitrogen, gases which respectively enter so largely into the 

 composition of water and our own atmosphere. 



The long debated question of the existence or non-existence of 

 a nebulous fluid in space is, then, for ever set at rest, and the 

 tendency of recent observations, although not absolutely proving, 

 yet goes very far to show by inference, that the constituents of the 

 world once existed in a gasiform condition, the elements being in a 

 " disassociated state of chemical indilierence to one another," 

 until a lowering of temperature brought about combination and 

 condensation. 



It requires but a slight stretch of the imagination to conceive 

 that the interplanetary and interstellar spaces are also occupied by 

 gases, in a state of extreme tenuity, and this view, which is 



