1881.] on the Teachings of Modern Spectroscopy. 507 



reduce tlio problem of tindiiig out this temperature to the much 

 simpler ouo of tiuding out the teuiperaturc of a giveu electric spark. 



I hope that the few facts which I have been able to bring before 

 you to-night have given you some idea of the important questions 

 which have been brought under the range of si)ectrosC()pic research. 

 Many of these questions still await an answer, some have only been 

 brouglit into the preliminary stage of speculative discussion, but the 

 questions have been raised, and the student of the history of science 

 knows that this is an important step in its development and 

 progress. The spectrum of a molecule is the language which tliat 

 molecule speaks to us. This language we are endeavouring to under- 

 stand. The unexperienced in a new tongue which he is trying to 

 learn docs not distinguish small differences of intonation or expres- 

 sion. The power over these is only gradually and slowly acquired. 

 So it is in our science. We have passed by, and no doubt still are 

 passing by, unnoticed differences which apj)ear slight and unimportant, 

 but which when properly understood will give us more information than 

 the rough and crude distinctions which have struck us at first. We 

 have extended our methods of research ; we have extended our power 

 over the physical agents ; we can work with the temperature of sun 

 and stars almost as we can with those in our laboratories. No one 

 can foretell the result, and i^erhaps in twenty years' time another 

 lecturer will speak to you of a spectroscoj)y still more modern in 

 which some questions will have received their definite answer, and 

 by which new roads will have been opened to a further extension of 

 science. 



[A. S.] 



