Every day of this critical week has seen a larger concentration between the Oise and the Marne, and an increasing number of combats and expeditions. The first essential was to have constant information of the enemy's movements; and this scouting work, though less sensational than some other parts of the air program, remains perhaps the most important of all. Then followed with growing vigor the development of the aggressive functions of the air service in which it became a sort of extension of artillery and cavalry and even of infantry. A single group in one day brought down six boche planes and three sausages, dropped seventeen tons of bombs in the region of Rheims, and tons on marching columns of the enemy in the neighborhood of Ville-en-Tardenois. "Our pilots," said a group commander, "had orders not to come back with a single cartridge or bomb, and you may take it from me that they do not waste their munitions on clouds." On Thursday another group commander, receiving news that an enemy column was stretched over three miles of a certain road, sent about fifty machines to deal with it. They charged as a squadron of cavalry would do, coming down to within twenty and even ten yards of the earth, and with bombs and machine guns effectually dispersing and demoralizing the graycoats. Many enemy planes and sausage balloons have been brought down, but that is in the circumstances a secondary effort. Lines of communication and rear camps and centres of the enemy also have been harried. On Friday no less than seventy tons and on Saturday sixty-two tons of explosives were dropped by airmen on German bivouac troops. IN THE MARNE VALLEY I went down to the Marne Valley yesterday afternoon and from the edge of a wooded hill looked across over part of the north bank where the Germans are established. Established is hardly the word, for everything is floating and provisional in this phase of the war, and it is more than ever invisible except where infantry actions are in course, because there are no fixed intrenched lines. I could not find any trace of the enemy on the opposite amphitheatre of hills, but an observer hanging above at the tail of a sausage balloon may have seen something, for from time to time the French guns blazed angrily over my head and buildings were on fire in the villages. In this winding stretch of the valley crests rise 500 feet above the broad, strong stream, and there are five or six miles between the two ridges. The French have guns and machine guns in position, and any considerable attempt to cross will be very costly. Two hundred Germans came over yesterday morning and are now more or less contented guests of the French Republic. But the enemy does not seem to contemplate an immediate passage, if at all. It would probably be tried further west at some point where the northern hills are more dominant. The section of the important objectives appears to lie in this direction.