September i6, 1909] 



NA TURE 



Sically reached. Thirty hours were spent in making 

 ccibservations there and ten miles beyond the camp, and 

 in taking photographs. No land could be seen. The 

 .minimum temperature recorded during the thirty hours 

 was —33° and the maximum — 12° (? ) F. A sounding 

 was made five miles from the camp, but bottom was 

 not touched at 1500 fathoms. The parly returned to 

 •Cape Columbia on April 23, and to the Roosevelt four 

 davs later. On July 18 the ship left Cape Sheridan 

 and arrived in Indian Harbour on September 6. 



The record of the expedition is a triumph for good 

 organisation and persistent endeavour, and though 

 •details of the scientific observations are not yet avail- 

 able, the narrative gives good reason for believing 

 that, so far as the time permitted, some valuable work 

 was accomplished. Commander Peary states that 

 Prof. Marvin and Prof. McMillan both secured 

 numerous observations of tidal and meteorological 

 conditions, as well as other data of scientific interest, 

 while Dr. Goodsell gave special attention to micro- 

 ■scopic work. 



Commander Peary's achievement has rendered un- 

 siecessary any further expedition to reach the North 

 Pole, so that attention may now be concentrated upon 

 systematic scientific work in the region of which a 

 preliminary view has just been taken. Whatever 

 ■may be the ultimate decision as to relative claims to 

 liave been the first to reach the pole, there can be no 

 doubt that the work carried on by the members of 

 Commander Peary's expedition w^ill be of greater 

 value to science than mere observations of latitude 

 taken during a " dash " to the pole. The success of 

 the expedition is associated, however, with a fatal 

 mishap to one of the scientific members. Prof. R. G. 

 Marvin, of Cornell University, was drowned on 

 April 10, forty-five miles north of Cape Columbia, 

 while returning from latitude S6° N. in command of 

 a supporting party. Prof. Marvin was only thirty 

 years of age, and his death has caused great regret. 



Though Commander Peary refers in his narrative 

 to observations for latitude made at various points, no 

 particulars are given, but that may be because the 

 narrative was written for the general public. The 

 exp-lorer has had a unique experience in Arctic 

 regions, and when his observations are published 

 thev will, it is hoped, show that the instruments used 

 and corrections applied enabled him to determine 

 position with reasonable accuracy. The determina- 

 tion of latitude by observations of the sun is, how- 

 •ever, very difficult in latitudes near the poles. Without 

 suggesting that Commander Peary's results may be 

 found to require correction, it is of interest to indicate 

 the conditions of observation in polar regions and 

 the instruments used by some explorers. 



L.wiTUDE Observations in Polar Regions. 



To an explorer situated at one of the poles of the 

 earth, the stars and all other heavenly bodies appear 

 to pass round him in circles 'parallel to the horizon 

 once in twenty-four hours, and the altitude of any one 

 star is the same at whatever time it might be taken, 

 provided the atmospheric conditions remain un- 

 ■changed. If an explorer could be at either pole during 

 the winter months, the best proof he could have that 

 'he had really reached go° latitude would be by ob- 

 servatio is of stars. Should he be able to measure the 

 altitude of a star with a theodolite or sextant and 

 artificial horizon, at not less than 35° above the 

 horizon, and repeat his measurement at regular in- 

 tervals, say, of three hours, during one complete 

 rotation of the earth, and find the altitude to 

 be the same at every observation, he would certainly 

 be at an extremity of the earth's axis. Should time 

 ■be pressing, instead of this somewhat lengthy opera- 

 Tsfo. 2o8t, vol. 81] 



tion he could take observations of different stars one 

 after the other around the horizon, and then if, after 

 applying corrections for refraction and instrumental 

 errors, he found in each case the altitude to be the 

 same as the declination of the star given in the 

 Nautical Almanac or similar publication, he could 

 conclude that he was exactly on a pole of the earth. 

 The former of these two would be the more satis- 

 factory method, because effects of refraction, which is 

 very uncertain in high latitudes, would be eliminated. 



But it is usually daylight when the explorer reaches 

 his highest latitude, and the stars are not visible, so 

 here is a practical difficulty in the way of either of 

 these methods. .Still, much the same plan could be 

 followed with the sun. If an explorer is exactly at the 

 pole the sun will pass round him in a circle in twenty- 

 four hours, and the only change in its altitude will be 

 due to the change in declination, which is given in 

 the Nautical Almanac for every hour. Should it be 

 found, then, during a series of observations of the sun 

 extending throughout twenty-four hours, or over a 

 number of hours, that the observations changed just 

 the amount of the sun's change in declination for 

 every hour, the only place where the observer could be 

 would be at the pole. 



If, instead of the altitude remaining the same, it 

 should, during one rotation of the earth, be found to 

 decrease for twelve hours and then increase for the 

 other twelve, or vice versa, it is clear that the latitude 

 would not be 90°, but its value could easily be com- 

 puted from the observations. 



As regards observations for time taken at or near 

 the poles, the ordinary method of taking sets of 

 altitude of east and west stars fails altogether, 

 for the simple reason that the altitude remains prac- 

 tically the same at all times, and it is impossible to 

 state the exact instant of time corresponding to a 

 certain altitude. The only satisfactory method of 

 rating a chronometer would be by taking transits 

 of the sun or stars by a theodolite firmly fixed and 

 left in position on a stand. Since all the meridians 

 converge at the poles, there can be no difference of 

 longitude, and another remarkable fact would be that 

 an observer exactly over the North Pole would be 

 facing south whichever way he turned, and this would 

 interfere with his ordinary idea of bearings con- 

 siderably. 



There can be no doubt that the best instrument to 

 take for accurate observations at or near a pole is a 

 good transit theodolite, and altitudes below 30° or so 

 should, if jossible, be avoided. With a sextant and 

 artificial horizon, a low altitude, such as 10° or 11° 

 or below, is very satisfactory. In the first place, it is 

 extremely difficult to make a contact at all, and then 

 the image in the artificial horizon is usually greatly dis- 

 torted, specially when a glass plate artificial horizon is 

 used, silvered only on the back. But whether the 

 observations are taken with a theodolite or sextant and 

 artificial horizon, it is naturally impossible to expect 

 any result that can be depended on unless a solid 

 foundation exists upon which to level up the theodolite 

 or place the artificial horizon. 



To take advantage of the best conditions of the ice 

 and ensure a safe return, a polar explorer endeavours 

 to reach his highest latitude at an early date when the 

 sun's declination is only a few degrees. Thus it was 

 April 7, 1895, when Dr. Nanscn arrived at 86° I2'3'N., 

 and .\pril 25, 1900, when Captain Cagni, of the Duke 

 of the Abruzzi's expedition, reached latitude 86° 34' N., 

 his farthest north ; whilst the two explorers whose 

 names are just now so prominent both announce that 

 they discovered the North Pole in this month. 



Although doubtless unavoidable for the reasons 

 stated, these comparatively early dates of reaching 



