52 WITH SCOTT : THE SILVER LINING 



above our explorer hits this celestial' sphere at Z. (The earth 

 is really a mere dot at O compared with this huge sphere.) 



Now we have a problem as clear as that involved in 

 determining latitude. The position of the sun (S) on the 

 sphere's surface is determined by the intersection of two lines, 

 PS and ZS. Of these PS is tabulated in the almanac, and 

 SZ, between the sun and the zenith (directly overhead), is 

 measured by the sextant. The remaining side PZ of the 

 triangle PZS is given by 90 minus the latitude EZ. Hence 

 PZ the colatitude is known from our previous calculation. 

 Given three sides of a triangle (even if it be on a curved 

 surface), we can, as in Euclid, determine the angle at the 

 pole ZPS. But this angle is the angle between the required 

 meridian of longitude PZE and the longitude of the localities 

 at that moment experiencing midday. It is extremely simple 

 to find out what the latter longitude is, since we know 

 Greenwich time from the chronometer. For suppose our 

 chronometer says it is seven in the morning at Greenwich, 

 then at this time it will be midday at 75 east (five hours 

 difference) at Bombay. If our angle ZPS turns out to be 

 ioo° under these conditions (and we know it is midday at 

 Bombay), our longitude is 75+ 100, or 1 75 ; about that of 

 Cape Crozier. 



I feel rather proud of this explanation. I have never seen 

 the problems so described before, and it has passed the critical 

 review of a navigator. May it help every reader who may 

 chance to be lost with a sextant and nautical almanac ! 



After the gale the dogs took some time to recover their 

 normal spirits. We had heard that the Peary dogs were 

 huge, ferocious beasts, ready to eat a man on sight. But 

 they tamed down wonderfully, and, truth to tell, seem some- 

 what afraid of the stockier Siberian horde. It is prophesied 

 that they will fall victims to the latter when shore fighting 

 starts, and consequently they may be sent with the Edward VII. 

 Land (or eastern) party. They are fed on biscuits, and 

 (lately) on seal meat, and are certainly not kept very hungry, 

 for one often sees a little food left. Poor Osman, the leading 

 dog, was very sick after the gale, and was accommodated with 

 some straw in an iron washing-dish. In this he curled up 

 snugly, and recovered in a few days. The ponies and dogs 

 consume about 80 per cent, of the drinking water ; but the 



