166 KECENT PROGRESS IN ASTRONOMICAL RESEARCH. 



varies often by amounts of 5 or 10 per cent, and that these variations 

 aifect temperature all over the earth, seems to be confirmed by these 

 measurements. 



Eesolutions were adopted by the Union advising the trial of several 

 kinds of investigation tending to confirm or disprove the supposed 

 variability of the sun, and a committee was charged with reporting 

 the best methods of procedure in observation and reduction of 

 measurements. 



Partly in response to the recommendations of the Union, and partly 

 owing to the interest displayed in the subject by some of the fore- 

 most astronomers and physicists of the time, new observatories have 

 recently been organized, chiefly for solar work, and older observa- 

 tories are beginning new" series of observations in this field. Most 

 notable, of course, is the Carnegie Solar Observatory on Mount 

 Wilson, in California, where daily photographs, both direct and with 

 the spectroheliograph, are being made, and where the determina- 

 tion of the time of rotation of the sun, the spectrum of sun spots 

 and its relations to the spectra of stars and terrestrial sources, besides 

 other interesting studies, are already being actively pushed. Solar 

 work of several important kinds has recently been begun, or is 

 about to be taken up, at a number of observatories in India and 

 Australia, some of which are supported by government. Our own 

 Government has for about fifteen years supported the Astrophysical 

 Observatory of the Smithsonian Institution, which has always been 

 a solar observatory, and now solar photographs are made regularly 

 at the United States Naval Observatory. It is also defuiitely 

 intended to undertake solar observations at the new Mount AVeather 

 station of the United States AVeather Bureau. 



In England and in Italy long series of records of solar phenomena 

 have been made by Governmejit and other observers ; and the counts 

 and drawings of sun spots have rewarded by substantial results the 

 patient persevering study, through years and decades, of many 

 noted European observers, both amateur and professional, including 

 Schwabe, Carrington, Wolf, Wolfer, Howlett, Sidgreaves, and others. 



Wlien so much of interest remains clearly waiting to be discovered, 

 and so many observers furnished with the powerful appliances of 

 modern astronomy and physics are enthusiastically entering the field, 

 it can not be doubted that the next few years will mark an epoch in 

 solar research. 



II. VARIATION or LATITUDE AND THE WANDERING OF THE POLE. 



In the Smithsonian reports for 1893 and 1894 appeared two arti- 

 cles by Sir Eobert Ball and Prof. J. K. Rees, respectively, in which 

 the then newly proved variation of latitude is described. While in 

 actual magnitude small, this wandering of the pole of the earth is so 



