422 THE POPULAR SCIENCE MONTHLY. 



should also be made of the unknown element conjectured by Huggins 

 to exist in some nebulae. This conception of a first matter or Urstojf 

 lias also been maintained by Ilinrichs, who has put forward an argu- 

 ment in its favor from a consideration of the wave-lengths in the lines 

 of the spectra of various elements. 



It is curious in this connection to note that Lavoisier suggested 

 that hydrogen, nitrogen, and oxygen, with heat and light, might be 

 regarded as simpler forms of matter from which all others were de- 

 rived. The nebula?, which we conceive as condensing into suns and 

 planets, show us only two of the three elements of our terrestrial en- 

 velope, which is made up of air and aqueous vapor. If now we admit, 

 as I am disposed to do with Mattieu Williams, that our atmosphere 

 and ocean are not simply terrestrial, but cosmical, and are a portion 

 of the medium which, in an attenuated form, fills the interstellary 

 spaces, these same nebulae and their resulting worlds may be evolved 

 by a process of chemical condensation from this universal atmosphere, 

 to which they would sustain a relation somewhat analogous to that 

 of clouds and rain to the aqueous vapor around us. This, though it 

 may be regarded as a legitimate and plausible speculation, is at pres- 

 ent nothing more, and we may never advance beyond conjecture as 

 to the relation of the various forms of so-called elemental matter, and 

 to the processes which govern the evolution of the celestial spheres. 

 You will, I trust, pardon this excursion to the regions of space and 

 the realm of imagination into which I have led you, and return with 

 me to the consideration of a new chapter in chemical theory. 



-- 



EEPLY TO THE CEITICS OF THE BELFAST ADDEESS. 1 



By JOHN TYNDALL, LL. D., F. E. S. 



I TAKE advantage of a pause in the issue of this Address, to add a 

 few prefatory words to those already printed. 



The world has been frequently informed of late that I have raised 

 up against myself a host of enemies ; and considering, with few excep- 

 tions, the deliverances of the press, and more particularly of the re- 

 ligious press, I am forced sadly to admit that the statement is only 

 too true. I derive some comfort, nevertheless, from the reflection of 

 Diogenes, transmitted to us from Plutarch, that "he who would be 

 saved must have good friends or violent enemies; and that he is best 

 off who possesses both." This "best" condition, I have reason to be- 

 lieve, is mine. 



Reflecting on the fraction I have read of recent remonstrances, ap- 



1 Preface to the seventh edition of the Address before the British Association at 

 Belfast, with an Appendix on "Scientific Materialism," etc. D. Appleton & Co. 



