It is hardly necessary to observe that neither of the maxims just mentioned was formulated with reference to problems which have only presented themselves within the last few years. The Romans, in the passage quoted, were thinking not of aerial space, but of the element which fills it. The old English lawyers were preoccupied with questions as to projecting roofs and overhanging boughs of trees. The problems now raised are admittedly incapable of solution _a priori_, but the difference between the two schools of thinkers is instructive, as bearing upon the extent to which those who belong to one or the other school would incline towards measures of precaution against abuses of the novel art. This difference was well summed up at one of our meetings by Professor Westlake as follows: "Conservation et passage, comment combiner ces deux droits? Lequel des deux est la règle? Lequel l'exception? Pour le Rapporteur (M. Fauchille) c'est le droit de passage qui prime. Pour moi c'est le droit de conservation." I am, Sir, your obedient servant, T. E. HOLLAND. Oxford, February 15 (1913). SOVEREIGNTY OVER THE AIR Sir,--Mr. Arthur Cohen has done good service by explaining that Great Britain has practically asserted the right of a State to absolute control of the airspace vertically above its territory. I may, however, perhaps be permitted to remark that he seems to have been misinformed when he states that the Institute of International Law has arrived at no decision upon the subject. The facts are as follows: The problems presented by the new art of aerostation have been under the consideration of the Institute since 1900, producing a large literature of reports, counter-reports, observations, and draft rules, to debates upon which no fewer than four sittings were devoted at the Madrid meeting in 1911. Wide differences of opinion then disclosed themselves as to territorial rights over the air, the radical opposition being between those members who, with M. Fauchille, the Reporter of the Committee, would presume in favour of freedom of aerial navigation, subject, as they would admit, to some measures of territorial precaution, and those who, like the present writer ("il se proclame opposé au principe de la liberté de la navigation aérienne, et s'en tiendrait[A] plutôt au principe _cuius est solum, huius est usque ad coelum_, en y apportant au besoin quelques restrictions," "Annuaire," p. 821), would subject all aerial access to the discretion of the territorial Power. The discussion took place upon certain _bases_, and No. 3 of these was ultimately adopted, though only by 21 against 10 votes, to the following effect: "La circulation aérienne internationale est libre, sauf le droit pour les états sous-jacents de prendre certaines mesures à déterminer, en vue de leur sécurité et de celle des personnes et des biens de leur territoire."