5 o WITH SCOTT: THE SILVER LINING 



the Pack for this relaxation. It is interesting to see how 

 tastes differ. Some swear by Conan Doyle and dislike 

 Merriman. Others find the White Company tedious (though 

 they are rare) and revel in biography. One officer — with an 

 eye to the penguins may be — is carefully perusing the 

 " Amateur Poacher," while all of us have studied the book on 

 Ski-Running. A most acceptable and suitable gift from Mr. 

 Reginald Smith and others was a complete set of those handy 

 sevenpenny and shilling books containing almost all the best 

 English fiction of the last fifty years. They are well printed, 

 fairly strong and not so valuable that one needs to don a 

 dress-suit to read them. The strong book cupboard (now on 

 the " balcony ") will be a most welcome addition to our 

 winter quarters during the long night. 



One problem, or set of problems, is engaging the attention 

 of every class of officer, be he doctor, biologist, or geologist. 

 It is that of field astronomy, for it is obviously essential that 

 each sledging party should be able to locate itself fairly 

 accurately by the sun or stars without reference to the natural 

 features. The latter will probably be uncharted, or — in the 

 Barrier and plateau journeys — non-existent. It is not a 

 specially easy business, but bulks largely in exploration, and 

 I should feel proud if I can briefly explain the two simplest 

 methods so that a layman can follow them. 



Latitude is distance (in angular measure) north or south 

 of the equator. The South Pole is 90 , and Melbourne 3 8° 

 (subtended at the centre of the earth). 



The sketch shows a vertical section through the earth, the 

 polar explorer being supposed at I in the midst of illimitable 

 ice plains. The position of the sun at midday is shown. 

 With a sextant or theodolite he measures the angle between 

 the horizon (H X H) and the sun (which equals SOH). He 

 knows the angle SOP ; for this is given in the nautical 

 almanac for the time of the observation. Now the angle 

 IOE is the required latitude, and we have all the data needed 

 to get it ; as thus : Latitude, IOE = IOS + SOE = (90 - 

 SOH) +(90° — SOP) (i.e. a right angle less altitude from 

 sextant, added to a right angle less the almanac angle). By 

 this short calculation the explorer can tell his exact distance 

 from the equator ; for a degree equals sixty-nine miles. 



But he does not know whereabouts is his position on 



