A difficult problem has a charm, by very virtue of its difficulty, which will attract and fix the attention of a eeltain class of mind. It is, moreover, a class of mind the world could ill dispense with, and which has conferred innumerable benefits upon mankind. It is mind which grapples with all questions, without regard to practical applications, is content to seek knowledge solely for the sake of knowing, leaving the useful applications of its investigations to another class of mind altogether. It is not inventive, but curious. It is sufficient that a thing is obscure, to secure at once the most ardent effort at solution from men of this class of mind. Of such sort is the intellect now grappling with what may be called, when it^ difficulty alone is considered, the great geographical problem of the age. It is hard for men of practical and inventive minds to see what earthly benefit can ever arise from these explorations. yet it would not be prudent to assert that no benefit could ever accrue, and many of the most proud mechanical, engi- neering,and chemical achieve ments of modern times have had for their germ, investigations seemingly as hopeless and im. practicable as this. Scarcely any scientific or literary periodical falls under our notice that does not bestow more or less of its space upun the subject of polar exploration. ' Pwtji-am's Monthly, for November, contains a long and interesting article on the “ ' Gateways to the Pole,” which maintains that the only true solution of the problem is that of Capt. Silas Bent. of “ Japan Expedition fame,” as put forth in an address, delivered by that navigator, before the St. Louis Historical Society. The date of Captain Bent's address is not given. The author conceives” the true Arctic pr blem to be, not whether there is a passage to the pole.” hut “ Is there a permanent and naoigable «wy to the pole? This question is answered in the affirmative by Captain Bent, who, in the absence of direct confirmatory experience, undert akes to prove, that, from the very nature of things, such a passage must exist. While we grant that the vast amount of heat, which passes into the sea at the equatorial regions, and passes to the north in the waters of the Gulf Stream, in the Atlantic, and the Kuro-Siwo, in the Pacific, would favor belief in the existence of open passages through which these waters find their way to the Polar Basin ; yet to argue. that because a thing is probable, it is real, seems more speculative than sound. The scientific world will be slow to accept the two “ gateways “ of Captain B ' ni till somebody finds them unlocked. This aspirant for Polar Honors not only believes that these avenues actually exist, but, to use his own language, “ the only practicable avenues by '^Mch ships can reach that open sea, and thence to the Pole, is by following the warm waters of these streams into that sea; and that to find and follow these streams, the water thermometer is the only guide, and that, for this reason, they may be justly termed ' the thermometric gateways to the Pole '." One would suppose, that if open and navigable parages really exist, they might be seen as well as determined by the thermometer. This latter, it strikes us, is what might be called feeling our way to the pole. We regard continuance upon the surface of the great streams alluded to, as entirely an unsettled question. The natural effect of heat upon the specific gravity of water would, if not counteracted by other influences, certainly keep these currents at the top ; but who shall l'ay, in the present state of ' our knowledge, that snch influences do not exist. Com. Rodgers made extensive deep-sea soundings in the Arctic Ocean, in 1856. He unifor nly found warm and light water at the top, cold and heavy water at the bottom, and warm and light water again beneath the cold middle stratum. An important fact was also discovered in these soundings, namely, that the outflowing surface currents were salter than the middle stratum. It is inferred from this fact, that the water in these surface currents flows into the Polar Basin in under currents,trom regions where much evaporation is going on, and where, consequently, a greater proportion of salt exists in the water than in oth er parts of the ocean. The subject of an open Polar Sea is discussed in Maury's “ Physical Geography of the Sea,” Chapter VII. It is there stated, that an under' current setting into the Polar Basin exists in Davis Strait, with a corresponding surface current flowing out, It is also It common thing for Arctic navigators to throw out; an wnchor upon icebel'iS floating north, impelled by these under currents,'and thus get their vessels towed north gratis by these ice tugs. Dr. Kane, in his narrative, gives a most graphic description o1 an adventure of this kind, whereby he secured consid, rable progress in spite of a head wind and strong opposing surface current. These facts show that Captain Bent's opinions are no less speculative than those of others who have preceded him. No amount of reasoning will convince thinking people upon this subject, no matter how plausible i.t may seem at first sight. Of all problems, the solution of which must depend upon J actual experiment, this one, obscured as it is by a multitude of unknown conditions, must be regarded as the chief.