198 



THE GUIDE TO NATURE. 



of these is that twilight lasts until the 

 sun is i8° below the horizon. Where 

 Dr. Cook spent the winter in Annotak, 

 there was some twilight even at the 

 very depth of winter. Secondly, the 

 mid-winter moon would be above the 

 horizon continuously for two weeks, 

 from first quarter through the full 

 moon to third quarter, and those who 

 have seen the full moon shining on the 

 snow will know how brilliant that 



the final dash like that accomplished 

 only by Cook and two Esquimos. The 

 ordinary navigator's sextant would be 

 too heavy and bulky, and would have 

 to be replaced by a less cumbersome in- 

 strument. Peary ordinarily carried a 

 small sextant, a so-called pocket sex- 

 tant. The ship's chronometer in its 

 square case, would give way to a good 

 pocket time-piece though two or three 

 small chronometers might be carried. 



Oct. Moon Phase:& 

 Last Qtr.,0ct.6. 



New Moon, Oct 14 

 First Qtr, Oct. ZZ. 

 Full AAoon. Oct. Z& 



Evening SkyMap for October 



NO RTH 



iPhases _^^^^^^^^^^^^^^^^ b p p 



Columbia 



■'*u.Ey v 



1 ,»\o, 





COMET. 



SOUTH 



would make the polar night. In addi- 

 tion to these two, there would be the 

 brilliant aurora borealis or northern 

 lights. But temperatures of 83 ° below 

 Zero Fahrenheit ! Not very many of 

 us would wish to experience a polar 

 winter. 



In the sledge trip to the pole, a dis- 

 tance about equalling that from Wash- 

 ington to Boston, no heavy instruments 

 could be carried, and especially so in 



The sea captain observes the altitude of 

 the sun by bringing it in contact with 

 the horizon where sea and sky meet. 

 But in the frozen north there is no such 

 horizon, the ice floes are thrown up 

 into hummocks and hills, and an alti- 

 tude of the sun above the visible hori- 

 zon would lead to inaccurate results. 

 On land explorations, an artificial 

 horizon is made by pouring mercury 

 into a little shallow tray. But mercury 



