Frequently a force, which has laboured under the impression that it is safe from detection, has revealed its presence unwittingly and upon the spur of the moment. If the men be steeled against the bomb attack, it is almost impossible to resist the inclination to take a shot when the airman, swooping down, ventures so temptingly near as to render him an enticing target almost impossible to miss. As a rule, however, the observer is on the alert for such a betrayal of a force's existence. When the bomb fails to scatter the enemy, or the men are proof against the temptation to fire a volley, a few rounds from the aeroplane's machine gun often proves effective. If the copse indeed be empty no harm is done, beyond the abortive expenditure of a few rounds of ammunition: if it be occupied, the fruits of the manoeuvre are attractive. Cunning is matched against cunning, and the struggle for supremacy in the art of craftiness is keen. The French Flying Corps have had recourse to an ingenious ruse for accomplishing two ends--the one to draw concealed artillery fire, and the other to pre-occupy the airmen. Two German aerial scouts observed a French machine flying at a somewhat venturesome height over their masked artillery. Divining the reason for the hostile intrepidity they gave chase. Circling round the French machine they assailed it with machine-gun fire. The enemy appeared to take no notice but continued his gradual descent in a steady line. Presently the German airmen, having drawn sufficiently near, observed that the French aviator was inert. Had he been killed? Everything pointed to such a conclusion, especially as they had raked the aeroplane fore and aft with bullets. But still suspicious they continued their circling movements, their attention so concentrated upon their quarry that they had not observed another move. It was the crash of guns from their masked artillery which broke in upon their absorption. Looking round, they observed three French aeroplanes soaring around and above them at high speed. Scarcely had they realised the situation before a spirited mitraireuse fire was rained upon them. One of the German aeroplanes was speedily disabled. Its fuel tank was riddled and it sank rapidly, finally crashing to earth in the deadly dive head foremost, and killing both its occupants in the fall. The second aeroplane hurried away with its pilot wounded. In the excitement of the aerial melee the first French aeroplane had been forgotten. It was now scarcely 100 feet above the German artillery. A capture appeared to be imminent, but the Germans received a rude surprise. Suddenly the aeroplane exploded and a hail of shrapnel burst over the heads of the artillerymen. The circumstance was decidedly uncanny, but after two or three such experiences of exploding aeroplanes the matter was explained. The apparently helpless aeroplane was merely a glider, which, instead of carrying a man, had a booby-trap aboard.