The German aëroplanes signal their observations by means of a code expressed in smoke balls. I never was able to obtain any theory as to how this code works. This method of communication seems to be very effective, as German shells sometimes arrive with singular accuracy and immediateness. It is commonly reported that Germans also signal with a suspended disc, but I have no personal knowledge of this system. The French had no definite means of signaling from the air in the early months of the war, and I believe this is still the case. They make their observation and return to their base to report, usually taking notes while aloft on maps and in note-books. I have no personal knowledge of the British methods. The Austrian system of signaling is by means of evolutions of the aëroplanes themselves. When they observe a target they fly over it, and when directly above make a sudden dip. They are observed during their evolutions with instruments, so that the exact angle and hypothenuse at the moment of this dip is known. They then make a circuit and come up from the rear and again fly over the objective. As they reach a point where they can see the target or objective their artillery opens fire and is corrected by the graphic evolutions of the aëroplane. If the shells drop too far to the left, the aëroplane turns to the right and the distance in profile that it travels before straightening out is the correction. They say, "Shoot short" by dipping and "Shoot farther" by rising. I have no knowledge of aëroplanes being used at night, although they sometimes return from daylight operations after night has fallen and make their landing with the assistance of beacons. It is commonly reported both by Germans and French that the steel darts used by the French aviators are the most effective offensive weapon so far used by aëroplanes. I have no personal knowledge on this subject. I have been several times informed upon reliable authority that the French have no particular instruments of precision for use in the dropping of bombs. At the commencement of hostilities the French aviators feared their own armies much more than they did the Germans, because the French had neglected to familiarize their troops with the designs of hostile aircraft. It was proved to be nearly impossible to force a fight with your enemy's aëroplane, even if he is far within your own territory. If your own aëroplanes are on the ground it takes them entirely too long to get to his altitude, and if he wishes to stay in the same neighborhood he himself keeps going higher as your aëroplanes mount toward him. There seems to be no difficulty encountered in avoiding aëroplanes already in the air, since they are usually visible at great distances. Anti-aircraft guns are generally mounted on automobile trucks, and are usually of small calibre. I have never seen any German aëroplanes other than monoplanes; these I have seen on ten or more occasions.