Just as it is true that to be well informed on any subject a man must read a great deal and be content not to have use for a great deal that he reads, so to secure good photographs of spots and scenes of note as he travels, he must make many negatives and be content to destroy many. The records of a second visit in better weather or at a more favourable season will supersede an earlier; typical groups more casual ones. The standard that he exacts of himself rises and work he was content with contents him no more. Sometimes one is tempted to think that the main difference between an unsuccessful and a successful amateur photographer is that the former hoards all his negatives while the latter relentlessly burns those which do not come up to the mark--if not at once, yet assuredly by and by. So the surprise that one feels at many of the illustrations in modern books of arctic travel is not that the travellers made such poor photographs but that they kept them and used them; for there can be no question that poor photographs are worse than none at all. CHAPTER XIII THE NORTHERN LIGHTS THE Northern Lights are a very common phenomenon of interior Alaska, much more common than in the very high latitudes around the North Pole, for it has been pretty well determined that there is an auroral pole, just as there is a magnetic pole and a pole of cold, none of which coincides with the geographical Pole itself. All the arctic explorers seem agreed that north of the 80th parallel these appearances are less in frequency and brilliance than in the regions ten or fifteen degrees farther south. It may be said roundly that it is a rare thing in winter for a still, clear night, when there is not much moon, to pass without some auroral display in the interior of Alaska. As long as we have any night at all in the early summer, and as soon as we begin to have night again late in the summer, they may be seen; so that one gains the impression that the phenomenon occurs the year round and is merely rendered invisible by the perpetual daylight of midsummer. [Sidenote: A GENERAL AURORA] The Alaskan auroras seem to divide themselves into two great classes, those that occupy the whole heavens on a grand scale and appear to be at a great distance above the earth, and those that are smaller and seem much closer. Inasmuch as a letter written from Fort Yukon to a town in Massachusetts describing one of the former class brought a reply that on the same night a brilliant aurora was observed there also, it would seem that auroras on the grand scale are visible over a large part of the earth's surface at once, whereas the lesser manifestations, though sometimes of great brilliance and beauty, give one the impression of being local.