¹ Montesquieu has many references to climate in his pirit of Laws. Earlier Jean Bodin, and others, linkedState and Soil in an environmentalistic way. The same trend is found in very recent works, especially by the late Ellsworth Huntington.

² See his Mainsprings of Civilization (NewYork, Wiley, 1945) where heredity plays a part. The danger for the geographer of studying the impact of physical conditions onhuman behavior is to be sucked into biological problems such asthe chromosomes’ or the genes’ reactions to changesin environment. This is not the geographer's field and, moreover, the modern trends of biology ought to induce the geographer to more and more caution in such an approach.

³ Arnold Toynbee's theory of “challenge and response” is, in a way, inverted environmentalism. Some statements in the early volumes of his Study of History worried us as granting far too much influence to physical forces, at the expense of other relations of the civilization considered.

⁴ It might be of interest to make a statistical analysis of the extent to which national boundaries have followed a crestline during different epochs of history and of the frequency of shifts in these crestline boundaries.

⁵ A good treatise on frontiers is Whittemore Boggs, S., International Boundaries: A Study of Boundary Functions and Problems, New York, Columbia University Press, 1940.Google Scholar It is well complemented by Jones, Stephen B., Boundary-Making: A Handbook for Statesmen, Treaty Editors and Boundary Commissioners, Washington, Carnegie Endowment, 1945.Google Scholar Frontiers area “technical” problem on which a great deal has been written. Curzon's, Lord Frontiers (Oxford, Clarendon Press, 1908)Google Scholar is well worth rereading. The international status of rivers is still one of the most delicate problems of international law; see Hall, William E., A Treatise on International Law, 8th ed., Oxford, Clarendon Press, 1924.Google Scholar

⁶ The whole problem of conservation of resources is intimately linked with economic geography and also with the foreign economic policy of the nations concerned. Too much literature has been recently published on this issue for a listing here.

⁷ See the remarkable analysis given by Viner, Jacob, “The Economic Problem,” in Nevi Perspectives on Peace, ed. by de Huszar, G. B., Chicago, University of Chicago Press, 1944, pp. 85–114.Google Scholar

⁸ Chinard, Gilbert in his book L'homme contre la nature (Paris, 1949)Google Scholar gives interesting examples fromAmerican history. We have also come to similar conclusions in our studies of Old World regions; see Gottmann, Jean, A Geography of Europe, New York, Holt, 1950.Google Scholar

⁹ See Cooper, John C., The Right to Fly, New York, Holt, 1947.Google Scholar It will probably be difficult for the laws of the air to remain in their present state. It seems hard to avoid putting a “ceiling on sovereignty” in the atmosphere, at some altitude, if some actual freedom to air navigation is to be instituted.

¹⁰ Hoover, Edgar M., The Location of Economic Activity, New York, McGraw-Hill, 1948.Google Scholar

¹¹ Blache, Paul Vidal de la, Tableau de la géographie de la France, Paris, 1902Google Scholar (the first volume of the monumental Histoire de France edited by Ernest Lavisse). The first chapters of this volume are a masterpiece and should be better known by geographers and political scientists.

¹² See Whittemore Boggs, S., “Geographic andOther Scientific Techniques for Political Science,” American Political Science Review, XLII, No. 2 (April 1948), 223–38.CrossRefGoogle Scholar

¹³ Vidal de la Blache, op. cit.

¹⁴ The Writings of Thomas Jefferson, ed. by Ford, P. L., New York, Putnam, 1899, X, 277–78.Google Scholar

¹⁵ In a recent article, Mitrany, David (“Evolution of the Middle Zone,” Annals of the American Academy of Political and Social Science, Vol. 271 [September 1950], pp. 1–10)CrossRefGoogle Scholar observes that the present “iron curtain” follows a ribbon of territory in Central Europe which has been a curtain stopping many streams in history: the Romans, Western Protestantism, and the industrial revolution could not expand much east of it; the Turks and the Eastern Church remained behind it. Such stubborn divides should be investigated thoroughly by geographers for whom they set interesting problems.

¹⁶ Demangeon, Albert, La Plaint Picarde, Paris, 1906.Google Scholar

¹⁷ Moodie, A. E., Geography Behind Politics, London, 1947.Google Scholar

¹⁸ The political geography of Turgot, A. R. J. is to be found in Oewvres de Turgot, ed. by Nemours, Dupont de, Paris, 1844, II, 611–26.Google Scholar

¹⁹ Recent technological developments have given rise to very complicated but most interesting new problems in the field of the law of the air. How far up does a national sovereignty extend in the space above its territory? With airnavigation and perhaps interstellar communications coming soon, space available to men has changed from a bi-dimensional to a tri-dimensional problem. Law has almost seemed to ignore the third dimension or, more exactly, has extended it to the infinite.If the column of space above a given territory belongs to that territory without restriction in distance, the moon's sovereignty changes as it circles around the earth, and so would any satellite of the earth. It does not matter today, but how could this be left open when men get to be actively sending rockets to the moon or creating new satellites. Physicists believe that such a situation is not too far in the future. Theproblem ofguided missiles passing over “neutra” territory is adifferent immediate problem in this same line, and the possibility of rain-making has recently shown in the vicinity of New York how disputed the control of the air is going to be. It has got to be both partitioned and governed according tolaws based on permanent moral principles rather than on a changing “power politics” situation.

See especially Cooper, op. cit. Several discussions of these matters with Mr. Cooper have greatly helped us to elaborate our own view of these matters.