THE 



POPULAR SCIENCE 



MONTHLY. 



JUNE, 1904. 



THE TOTAL SOLAE ECLIPSE OF AUGUST 30, 1905. 



By Professor W. W. CAMPBELL, 



DIRECTOR OF THE LICK OBSERVATORY, UNIVERSITY OF CALIFORNIA. 



f I THE last total eclipse of the sun observed was that of May 17, 

 -*- 1901, whose path crossed the islands of Mauritius, Sumatra, 

 Borneo and New Guinea. Its durations, in Sumatra six and a half 

 minutes, was the greatest of any observable eclipse of the last half 

 century. The shadow touched the islands at very few accessible points, 

 and the choice of observing stations was unusually limited. Never- 

 theless, observations were undertaken by a relatively large number of 

 well-equipped expeditions from this country and Europe. At nearly 

 all stations clouds of various degrees of thickness covered the eclipsed 

 sun, and the work was seriously hampered by them. Fortunately, 

 many valuable photographs were secured through thin clouds. For 

 example, Professor Perrine, in charge of the William H. Crocker Ex- 

 pedition from the Lick Observatory, obtained results of great value 

 with each of his ten instruments, though only five to twenty-five per 

 cent, of the light passed through the clouds. In fact, it would be diffi- 

 cult to say wherein they could have been better, except that the intra- 

 mercurial planet search was incomplete in one third of the area called 

 for in the program. 



A total eclipse, of short duration, occurred on September 20, 1903, 

 in the southern Indian Ocean. The shadow did not pass over land, 

 unless within the closed south polar continent, and no effort was made 

 to secure observations. 



A long eclipse will occur on September 9, 1904. It, too, will come 

 and go practically unobserved, for its path passes eastward over the 

 central Pacific Ocean without touching any known islands, and ter- 

 minates on the coast of northern Chile about six minutes before sunset. 



VOL. lxv. — 7. 



