INDUSTRIAL PROGRESS DURING THE YEAR 1873. xxi 



octavo, with nearly two hundred drawings relating to spots 

 on the planet Mars. The publication of this important work 

 has been undertaken by the Belgian Academy of Sciences. 



The general mechanical problems relating to the stability of 

 the solar system have received much attention from Mr. Stock- 

 well in a memoir published by the Smithsonian Institution. 



The mathematical theory of the motion of the moon is, as 

 announced by Professor Airy, in an extremely unsatisfactory 

 condition, and he expresses grave doubts as to the value of 

 any attempts that have been made to restore ancient his- 

 torical dates by reference to astronomical computations of 

 recorded eclipses of the sun or moon, a doubt which extends 

 even to his own previous investigations, which latter liave 

 been very generally accepted as valuable contributions to 

 ancient chronology. 



The existence of an atmosphere around the moon has been 

 rendered quite probable by the investigation of Neison, who 

 has shown that one whose density is the four-hundredth part 

 of that of the earth will by its refraction explain certain 

 anomalies in the observations of occultations of stars. 



In reference to solar physics, the year has witnessed im- 

 portant contributions, among which will perhaps take first 

 rank that full discussion that has been carried on in reference 

 to the various theories of the physical constitution of the sun, 

 that has been prolonged throughout nearly the whole year 

 at the successive sessions of the Paris Academy of Sciences. 

 In this very important discussion, nearly every question re- 

 lating in any way to the j^roblems of solar physics and the 

 spectroscopic method of research has been fully debated. In 

 connection with this, it is announced that Faye, abandoning 

 the theory of uprushing gases, has virtually adopted, in the 

 essential points, that proposed by English observers. 



Zollner has contributed important ideas on this matter in 

 successive papers on the temperature of the sun, and the in- 

 fluence of temperature on the spectrum lines and bands. 



The observations of Rosa, which in the hands of Secchi 

 appeared to give as a result a variation in the solar diameter 

 dej^ending on the configuration of the solar spots, have been 

 completely analyzed by Auwers, who, from an investigation 

 of all reliable observations of the solar diameter, demonstrates 

 that we have no reason to believe in such a variability. 



