A restriction on the use of balloons for bombardment of open places was, however, introduced in the Laws and Customs of War on Land. Article 25 of this convention of 1899 provided:

The attack or bombardment of towns, villages, habitations, or buildings which are not defended is forbidden.

Article 25 of the same convention of 1907 provided: The attack or bombardment by any means whatever of towns, villages, habitations, or buildings which are not defended is forbidden.

The introduction of the clause by any means whatever is significant, but it must be observed that the prohibition extends only to places that are undefended and does not apply to fortified or defended positions. Accordingly, so far as the conventional laws of war are concerned, there is no prohibition of the use of balloons or other air craft for purposes of observation, scouting, and the like at any point, though doubtless neutrals have the right to regulate the use of the air space above their territories, and to exclude air craft which would use that air space for hostile purposes. There is no conventional prohibition of the use of air craft for the bombardment or attack upon fortified or defended places. The proposition of Lord Reay, of the British delegation to the Second Hague Conference in 1907 to the effect that the prohibition of aerial warfare and the restriction of warfare to land and sea would be a step in the direction of limitation of armaments did not meet with enthusiastic response.

Changed conditions since 1907.-The discussion at The Hague conference in 1907 and elsewhere at about the same time showed that on the part of many states the willingness to put restrictions on the use of air craft in time of war was due to the belief that they could not be effectively controlled. Since 1907 the progress in methods of aerial navigation has been so great that the conditions are now entirely changed. Air craft ascend to heights that were thought impossible, make flights against contrary winds, cross channels and seas, and go over mountains with such ease as to disturb well matured

war plans, are launched from and light upon decks of war ships, and in fact have become an agency which must be seriously considered in time of war.

The opposition to the use of air craft which was common before 1907 often had as its basis the contention that the use of such means in war would be at too great a risk to those who were not directly concerned in the war. It was maintained that the noncombatant population and property would be unduly endangered by the discharge of projectiles from balloons. The dirigibility of air craft recently constructed has removed many of these objections.

In case of a battle on the high sea between two fleets many of the objections to the use of air craft for the discharge of projectiles and explosives would not hold to the same degree as in land warfare.

The amount of goods which may be carried in an air craft at present is not large, but the risk to the belligerent is not always determined by volume. The character of the goods may be the essential point. Information may easily be carried which may determine the issue of a campaign.

While there has developed a considerable opposition to the exercise by air craft of ordinary war rights of attack and defense by means of projectiles it has been generally recognized that the belligerent must be able to use such force as he possesses against air craft which serve as scouts or may otherwise afford information to the enemy which may be of vastly greater importance to the enemy than any amount of material goods. The nationality of such air craft may be of importance for the court, but for the commander of the forces the main object is to prevent the furnishing of information which may defeat or upset his plans.

Position of France, 1907.-M. Renault, of the French delegation to the Second Hague Conference, speaking of the discharge of projectiles from balloons or other air craift, said:

Peu importe la mode d'envoi des projectiles. Il est licite d'essayer de détruire un arsenal, ou une caserne, que le projectile

employé dans ce but provienne d'un canon or d'un ballon; il est illicite d'essayer de détruire un hôpital par un procédé comme par l'autre. C'est là l'idée essentielle à laquelle nous estimons que l'on doit s'arrêter. Le problème de la navigation aérienne fait de tels progrès qu'il est impossible de prévoir ce que l'avenir nous réserve à ce sujet. On ne peut donc légiférer en connaissance de cause. On ne peut s'interdire d'avance la faculté de profiter de nouvelles découvertes qui ne toucheraient en rien au caractère plus ou moins humanitaire de la guerre, et qui permettraient à un belligérant d'exercer une action efficace contre son adversaire tout en respectant les prescriptions du Règlement de La Haye. (Deuxième Conférence Internationale de la Paix, Tome III, p. 152.)

The rapid development of aerial navigation has shown the wisdom of M. Renault's position in 1907. The increasing range of flight of air craft that are under control of the navigators has changed the problem of aerial warfare. Aerial corps in some form are now common adjuncts of military forces. The predictions of a few years. ago in regard to the use of the air by man are in many respects more than realized. How far the use of air craft in war may be restricted by conventional agreement remains undetermined. Precedent seems to show that states are inclined to use against their enemies such force and such agencies as are under their effective control so long as these are not from their nature repugnant to the sense of humanity. Attempts were made to prohibit the use of torpedoes, submarine boats, and in earlier days. firearms. In the actual effect of a projectile there may be little difference when it is fired from a gun several miles distant so as to fall within a certain area or dropped from an air craft a few hundred feet above the area. In firing upon air craft the motion of the target may be in any direction in space, while in a naval vessel the motion of the target is in the main upon a plane.

These new conditions of possible warfare show that the rules for warfare on land and on sea may not be adequate for the regulation of conduct when the extended use of the air is involved in hostilities. The changed attitude toward aerial warfare was shown in the difference in opinions of delegates to The Hague conference in 1899 and in 1907.

As Dr. Alex. Meyer, of Germany, says, in 1899 men were willing to prohibit the discharge of projectiles from balloons for a limited period, because it was felt that the lack of control of the balloon made it a cause of unnecessary danger if its use should be unrestricted. With the development of means of control of balloons and the advance in construction of dirigible air craft many of the reasons for the restriction of their use in war have disappeared.

(Die Luftschiffahrt in kriegsrechtlicher Beleuchtung, p. 13.)

Aerial navigation conferences.-The aeronautical congress held at Nancy from September 18 to 24, in 1909, expressed the wish:

1. Que les États, renonçant aux mesures prohibitives, s'entendent pour réglementer la circulation aérienne dans un sens libéral protégeant leurs droits de défense par toutes les vérifications utiles, en assurant l'observation de leurs lois douanières par des mesures appropriées à la matière, comme il a été fait pour les véhicules automobiles.

Le Congrès reconnaît que la matriculation des aéronefs serait la meilleure et peut-être la seule manière d'assurer l'efficacité d'une réglementation libérale.

2. Qu'en vue d'éviter les accidents et collisions, la circulation des navires aériens soit l'objet d'une réglementation internationale établie en s'inspirant, autant que possible, du réglement international, depuis longtemps éprouvé, relatif aux abordages en mer, et en tenant compte des règles déjà pratiquées dans la navigation aérienne.

3. Que, en raison de l'importance des connaissances météorologiques pour la navigation aérienne, la météorologie prenne une place toujours plus considérable dans l'enseignement.

(Revue Juridique Internationale Aérienne, 1ere Année, p. 33.)

Opinion of Dr. Hazeltine.-Dr. Harold D. Hazeltine, of Cambridge University, in lectures delivered late in 1910 and recently printed, touched upon some of the phases of aerial jurisdiction in time of war. His views may be stated somewhat in extenso in his own words:

In considering the rules of international law in times of war it is important to have clear ideas as to the aerial space that can legally serve as the theater of war and the base of warlike operations. It is admitted by all that the aerial space above the

territory and territorial waters of belligerents and also the aerial space above the high seas will in the future be legally the proper space for belligerent activities. A more difficult question arises with reference to the aerial space above the territory and territorial waters of neutrals. If the theory that the air is completely free be adopted, one would necessarily be obliged to admit that the entire aerial space above neutrals should also fall within the field of warlike operations. So, too, if one adopted the view that the territorial State has only a limited zone of protection above its territory, or even if the territorial State had only a limited zone of sovereignty, the logical conclusion would be that all the upper strata of the air space above the neutral's territory should be a legitimate field for the operations of the belligerent powers. But, so far as I know, all the adherents of the freedomof-the-air position do not take this last logical step in their argument. They admit that the aerial space above neutrals should not serve as a space for the carrying on of hostilities by the belligerents. This admission on the part of the adherents of the freedom doctrine is a most important one; and, strictly speaking, I can not see in principle why they should not also admit the same considerations to apply in times of peace as in times of war. But this, of course, they do not admit! On the doctrine of the territorial State's full right of sovereignty in the entire air space above its territory and territorial waters, it is quite clear that this entire neutral air space could never serve as a space for actual hostilities between belligerents. In my opinion this latter is the sound view.

But although hostilities can not actually be carried on in neutral aerial space, a further question arises as to whether this neutral air space should be in other ways open to the use of belligerents. An examination of the present rules of maritime international law will assist us to an answer. Our fundamental question will be whether present rules of maritime international law should be adopted for future aerial international law. Present maritime international law lays down certain very important provisions favoring belligerents. It is not considered a violation of neutrality if a belligerent sea war vessel simply passes through the territorial waters of neutrals. So, too, the entry into neutral ports is not viewed as a breach of neutrality in case the entry is made for the purpose of obtaining provisions or of carrying out necessary repairs. Should these same principles apply in aerial international law?

The fact that territorial waters are in a sense a part of the sea, viewed as an international highway, lies perhaps at the basis of the rule that belligerent war vessels should have the right of passage through neutral territorial waters. Probably a distinction could be drawn between neutral territorial waters and the