52 ASTRONOMY 



Practical Astronomy. Among astronomical instru- 

 ments of French invention, mention may be made of 

 the equatorial coude of LOEWY and PUISEUX; the in- 

 dependent design of the spectroheliograph by DESLAN- 

 DRES (at practically the same time as by the American 

 HALE); the " spectroenregistreur des vitesses" of 

 DESLANDRES; and the recent use of the " astrolabe a 

 prisme" in the determination of latitude and time. 



In spectroscopy, the French contributions to the 

 development of the science have been very great. In 

 solar physics, they include the discovery of the spectro- 

 scopic visibility of the solar prominences, independently 

 of solar eclipses, by JANSSEN in 1868 (also made inde- 

 pendently by LOCKYER in England) ; the recent researches 

 of DESLANDRES (whose spectro-heliograms are in many 

 respects of unrivalled excellence) upon the upper layers 

 of the solar atmosphere and the relative motion of their 

 parts. In stellar spectroscopy, they include the 

 FIZEAU extension of the DOPPLER principle, which made 

 possible the whole movement for the spectroscopic de- 

 termination of radial velocity; the discovery of those 

 remarkable bodies which are still known, in honor of 

 their discoverers, as the WOLF-RAYET stars; the spectro- 

 scopic work of HAMY; and the work of FABRY and his 

 collaborators on the Orion nebula. 



In astronomical photography, France occupies a 

 leading position. This is perhaps natural, because the 

 development of photography is in so large a part due to 

 the French. The Atlas of the Moon, by LOEWY and 

 PUISEUX, is the standard in its field; the solar photo- 

 graphs of JANSSEN are in a class by themselves; but 

 above all other work in importance towers the " Carte 

 Photographique du Ciel," which, as its name implies, 

 owes its inception largely to French influence. The 

 headquarters of the international committee which 



