14 President's Address 



A series of observations for the determination of the differ- 

 ence of longitude between Melbourne and Adelaide by aid 

 of the Electric Telegraph, was made at the latter part of last 

 year, and although the result is considered not quite conclu- 

 sive, as it is intended to make another series of comparisons, 

 it may however be accepted as nearly the truth, and makes 

 the difference of longitude 25m. *33*78s. assuming the longitude 

 of Melbourne to be correct, that of Adelaide would be 

 9h. 14m. 2102s. 



Before leaving the subject of our astronomical labours, I 

 would add a word concerning the total eclipse of the sun, 

 which will take place on the 17th of August, this year. 



The eclipse will be a most remarkable one, and unrivalled 

 by any recorded in the annals of mankind in its magnitude 

 and duration. At its commencement the moon will be un- 

 usually near the earth, and at the same time reaches the 

 ascending node of her orbit. The sun also reaches nearly 

 the zenith of those places where the eclipse takes place at 

 noon ; the augmentation of the moon's apparent diameter, 

 due to her altitude is a maximum ; a combination of circum- 

 stances resulting in the apparent diameter of the moon 

 exceeding that of the sun by an unusual amount, and in the 

 time during which the sun will remain eclipsed, being almost 

 unprecedented. 



The greatest length of totality will occur in longitude 

 102° 38' E. and 10° 28' N. in the Gulph of Siam, where it 

 it lasts 6m. 50sec. The path of totality, which commences at 

 sunrise in Abyssinia, passes over the Straits of Babel Mandeb, 

 Aden, Arabia, through India between Goa and Rajapoor, 

 across the Gulph of Siam, where the greatest phase occurs — 

 then through Borneo, the whole of the South of New Guinea, 

 ending at sunset about the New Hebrides. 



So unusual an eclipse as this is sufficient to put astrono- 

 mers on the qui vive, for such an one has probably never 



