JV ADVEKTISEMENT. 



sliiirt \v:ivfli'iii;llis, and tlie iiiitlior was ubliget.1 tu devise an iiiipins I'd iiulLtid of 

 coatiiii,' tlie plates used in his investigation. 



This memoir contains an account of the special apparatus and nietliod <•[ using 

 it and continues with a description of the emission and absori)tion spectra of 

 oxvgen, nitrogen, hydrogen, carbon monoxide and dioxide and aqueous vapor for 

 wave-leno'ths reaching in the case of hydrogen to about 0.10 micron. Illu.stiations 

 of the apparatus and spectra accompany the text, and it is thought the whole will 

 be a valuable contribution to knowledge, though but preliminary to the researches 

 Doctor Schumann alone is continuing in this spectral region. 



In accoi-dance with the rule adopted by the Smithsonian Institution, the WDrk 

 has been submitted for examination to a committee consisting of Doctor Carl Barus 

 of Brown University and Mr. C. G. Abbot of the Smithsonian Astrophysical 



Observatory. 



S. V. Langley, 



SECKETAKV. 



Siiiitlisoniaii Institution, 



Washington, September, IflCS 



