The last day or two we have been on patrol duty in a fighting machine over a given area. This consists in flying all over the shop, and protecting our machines which are doing fire control, or photo, or reconnaissance work, or other special jobs; the ‘protection’ consists partly in drawing the fire of the ‘Archies’ (i.e. the regular anti-aircraft shrapnel quick-firing guns) and ‘Crumps’ (i.e. Howitzers which fire high-explosive shells from 5 to 8-inch) and partly in keeping off Hun machines from being too inquisitive as to the doings of our aeroplanes and the movements of troops on our side of the trenches. The area one covers varies, but is often about 50 square miles, and one’s air-speed varies from 45 to 75 miles per hour, except when diving, when the speed goes up beyond the range of the indicator, say up to 125 m.p.h. To this may be added, or subtracted from it, the part or whole of the true wind-speed—according to one’s course in relation to the wind. In windy weather this has often meant an additional 50 miles per hour, so our speed over the ground is frequently up to the standard of the police-trap at home! One sometimes covers a couple of miles on the floor in a minute or less, the height varying according to the day, etc., between about 5000 and 10,000 feet. This is fairly high up, but occasionally we have to go to 12,000 or even 15,000, though I have never had to do so yet. At these great heights we climb slowly and the engine and oneself both prefer to keep one’s level, as it is hard work for both to get up much beyond this, and it is very cold too. The anti-aircraft shells can reach us even here, though not very easily. The chief actual result of Patrol Orders is that we are on the look-out for Huns in the air, and ‘Archies’ and ‘Crumps’ too. Whenever we see the former we go for them, not necessarily direct, but often manœuvre a lot for tactical position first. Very often, if the weather is good, we take a few assorted bombs to drop, in case a good target appears over the Hun lines. They weigh a lot, and so we like to get rid of them as soon as possible. There is a gunner to work the guns, and he is either an officer or a specially trained mechanic, with a straight eye and no nerves. * * * * *