CHAPTER XIV 



Interesting Scientific Work in the Arctic 



THE scientific methods used by a polar explorer in determining 

 his position are practically the same as those employed by a 

 navigator in ascertaining his location at sea. The instru- 

 ments are the same in design, but necessarily vary slightly in 

 construction on account of the rough usage and extremely low tem- 

 peratures to which they are subjected. 



The most important of these in- 

 struments is the sextant, a light- 

 weight, portable instrument for 

 measuring the altitudes of the 

 heavenly bodies, the sun, moon and 

 stars, above the horizon, or their 

 angular distance as seen in the sky. 

 This instrument consists of a small 

 telescope and a series of mirrors, by 

 means of which the angle between 

 the heavenly body selected and the 

 horizon may be read on a gradu- 

 ated scale in the form of an arc 

 attached to the instrument. 



On shipboard the material used in the sextant is brass or 

 bronze, but for ice traveling in late years aluminum has been em- 

 ployed. 



Other necessary instruments are chronometers, or large 

 watches, with compensating balance wheels, constructed for ex- 



(203) 



SEXTANT. 



Instrument by Queen & Co., 

 Philadelphia. 



