The first duty to which I was assigned was "réglage," and this, I found, involves many complications. The chief source of trouble usually is the wireless apparatus, which has to be maintained in perfect working order. Before leaving the home field you usually circle over it, while your observer tests his sending apparatus. The receiving operator then answers by visual signals. Usually these are large white sheets laid on the ground in different formations, which have a prearranged meaning. When the radio is found to be in perfect order you are off to the battery you have been ordered to co-operate with. By wireless your observer then reports to the battery commander, and receives his orders by means of the same visual signals. You then head in the direction indicated to you before leaving, and, hovering over the position to be bombarded, the observer signals back "fire." The moment the shells have landed you turn quickly about and inform the artillery just how many metres their fire was long, short, or to the right or left. Your message is once more answered with the sheets. Again you fly back toward the enemy’s position, circling in this way backward and forward between the battery and the target until the réglage is completed. Naturally every care must be taken not to disclose the position of your own guns to the enemy, or retaliation—"strafe," the English call it—summarily follows. Sometimes it is the battery which interrupts the work with the signal, "Avion ennemi," when the fire instantly ceases until the German aeroplane has disappeared or been driven off. With such occasional interruptions the work continues until your observer can send back the signal "fire correct," which is generally answered by the "sheet signal" with the information that you may return home. Until this dismissal occurs, however, the ground below wholly engrosses the attention of your observer. You yourself are forced to keep a close watch for Boche fighting-machines so as not to be caught unawares by one of them. This is often a very trying task, as the models of some of the French and German aeroplanes are so very much alike that they cannot be distinguished until they are within range. The tricolor cockade and the black iron cross painted on the top and bottom of each wing serve to identify the fliers of the two belligerents, but these colors cannot be seen very far. You consequently have little warning as to whether the approaching planes are friends or foes. Sometimes the enemy’s anti-aircraft batteries become a bit too familiar. On such occasions the observer tries to signal to his batteries to drop a shell or two where these pieces are mounted. Often quiet is not restored until the machine has been more or less riddled with shrapnel bullets. One réglage is very much like another, and when you have read the description of one you become familiar with them all. It is only in the results accomplished that the details vary.