ANNIVERSARY ADDRESS. 21 



In Astronomical Science the year 1887 will be marked as that 

 of the first great Conference of the World's Astronomers — a 

 Conference called together to secure systematic and united effort 

 in carrying out the grandest work that astronomers have ever 

 attempted : that is, to make a complete and accurate chart of the 

 whole heavens down to the stars of the 14th magnitude. Some 

 idea of the dimensions of this undertaking may be gained from 

 the fact that, as I am informed by Mr. Russell, Government 

 Astronomer, when all who can take part in it are ready, which 

 will probably be in the year 1889, it will take from six to eight 

 years to get the 50,000 photographs which this work involves. 



Many of these photos will record thousands of stars, and the 

 whole record is estimated to contain 20 millions. And after that 

 comes the labor of measuring, recording and publishing the 

 position of every individual star ; no one yet dares to say when 

 that will be done, but when all the labour has been done, and the 

 few final figures for each star are printed, they alone will give 

 about 2,000 quarto volumes of 300 pages each. 



But the fact that this work is to be undertaken, marks a great 

 step onward in the appliances now at the command of the 

 astronomer, resulting from recent advances in photography, 

 optical work and mechanism, but mainly in photography. 

 Sensitive plates are now made of such marvellous quality, that 

 stars and nebulae invisible even with the most powerful telescopes, 

 can be photographed ; and by the aid of new appliances the 

 veteran solar photographer "Janssen" proposes to get photos of 

 the Sun which will reveal every detail of the changes constantly 

 going on in it, and thus lead the way to answer the question 

 which the meteorologist is asking, " What is going on in the Sun 

 to account for these strange conditions of weather 1 And there 

 can be no doubt that the great impulse now given to astronomy 

 by the work of the Paris Conference, will do very much towards 

 tracing the solar conditions, which are of such vital importance 

 to the inhabitants of the earth in their effect upon climate. 



