148 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1937 



once every other year. In the years 1900-36, expeditions have 

 attempted observations on IS separate eclipses. 



In a third of a century there were five total eclipses observed in 

 the United States, those of the years 1900, 1918, 1923, 1925, and 1932. 

 but in the coming half-century only the two echpses of 19G3 and 1970 

 can bring scientific results of value, though two other eclipses in 1945 

 and 1954 will begin at sunrise about on the Canadian border. Hence, 

 the present generation of American eclipse observers must make 

 long trips from home if the scientific reputation of the country is to 

 be maintained. 



The total number of eclipses, solar and lunar, partial and total, 

 that may occur in 1 calendar year varies from a minimum of two to 

 a maximum of seven. The number of solar eclipses in a year varies 

 from two to five. In the years 1922, 1920, 1929, 1933, 1940, 1944, 

 1951, and 1962 there are two eclipses only, both of the sun. In 1935 

 there were two lunar and five solar eclipses, a combination that will 

 not take place again until the year 2485. In 1982, there wiU bo tliree 

 total lunar eclipses and four partial solar eclipses. 



Taking the earth as a whole, there are more solar eclipses than 

 lunar in the ratio of 4 to 3. It has been calculated that on the average 

 a total eclipse of the sun \'isits a locality once every 360 years. The 

 maximum duration of totality at a solar eclipse is 7 minutes 30 

 seconds. On June 8, 1937, totality will last 7 minutes 4 seconds. 

 The eclipse may be observed from a few small islands in the Phoenix 

 group about 8 o'clock in the morning when totality will last a little 

 more than 4 minutes. Tliirty-five minutes before sunset the eclipse 

 will reach Peru, where duration is 3 minutes 20 seconds, and an altitude 

 of the sun of only 8° will make scientific observations difficult. 



The inhabitant (and we believe there are none) on Jupiter or Saturn 

 would have frequent opportunities to observe total eclipses, both of 

 the sun and of the moons. If our own fair Luna were 25,000 miles 

 farther off from the earth, or if its diameter were 10 percent smaller 

 there would never be a total solar eclipse. What a dreary old world 

 this would be, especially for poets and lovers, if the earth resembled 

 Venus in having no moon! 



TIMES OF CONTACTS 



The position of the moon is furnished from the times of contact of 

 the limbs of the sun and moon. The time of first contact, or the 

 beginning of the eclipse, is difficult to observe visually with accuracy, 

 since nothing is to be seen at the edge of the sun until the moon is 

 projected on the sun's face — and first contact has actually taken place. 

 Fourth contact, the end of the eclipse, is easier to observe, since the 

 moon may be followed in a telescope of low power until it leaves the 

 face of the sun. Second and third contacts, the beginning and ending 



