78 PROFESSOR HENRY ALLEN HA/EN 



jilane of the equator passes througli the sun ; but this has been shown 

 by observation to be impossible at the time of the winter solstice. 

 On that date the sun is 23° south of the equator. The axis of the 

 earth must therefore be tilted 28° from the vertical and away from 

 the sun in order to imitate actual conditions. 



As the prolonged axis meets the sky in the same point at all 

 seasons of the 3'ear, the attitude of the axis must alwaj's be parallel to 

 its initial position. Carry the earth around its orbit, holding the axis 

 l)roperly on the way, and observe the relative attitude of the day and- 

 night circle at difierent times of year. All the j)eculiar variations of 

 the sun's midday altitude, of the times and directions of sun rise and 

 set, and of the length of day and night can be explained by this little 

 working model ; lience it maN' be fjiirly said to present the conditions 

 of nature. It is well that the scholar should know that it is entirely 

 on the basis of such agreements between hypothesis and fact that 

 text-books make statements al)0ut the inclination of the earth's axis, 

 the duration of its annual revolution, and so on. There is no other 

 door by which one can really enter the domain of knowledge, where 

 the motto is written : " Truth for authorit}', not authority for truth." 



When Iteginning to prepare this article it was my intention to cover 

 other l)ranches of the subject as well as those here treated, but on 

 advancing into the manuscript it has seemed better to expand general 

 recommendations into somewhat specific explanations in order to 

 aid in carrying them into practice. Thus the article has grown un- 

 duly long. .Something al)out practical exercises on the oceans and 

 the lands may l)e presentdl at another time. 



PROFESSOR HENRY ALLEN HAZEN 



l>y !i j^ail iicciclent on tlie eveiiiiij.' of .Monday, .luiuuiry 22, UtOO, the U. S. 

 Weather Bureau lot-t one of its most prominent otticials and the National Geo- 

 grapliic Society one of its active members. Professor Hazen, wliile ridinj; on 

 his l)icycle, hastening? to his night work at tlie Weatlier Bureau, collided with a 

 l)edestrian and was dasheil to the ground. He received injuries from wliich he 

 «lied twenty-four hour;^ hiter. 



Professor Ha/en was born .January 12, 1S49, in Sirnr, India, al»out 100 miles 

 east of Bombay, and was the son of Rev. Allen Hazen and Martha Cliapin, his 

 wife, missionaries of the Congregational Church. He came to this country when 

 ten years old, and was educated at St Johnsbury, Vermont, and at Dartmouth 

 College, where he was graduated in 1871. For some years he was instructor in 



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