The Boches have such machines,--particularly the Rumpler,--which are tough nuts to crack, even when outnumbered. Two of our boys had a running fight with a Rumpler recently, and dove at him alternately for thirty minutes over forty miles of country. Both were nearly brought down in the process--and they failed to bag the enemy machine, though at the last they did for the observer. This shows the great value of the fast two-place bus. I doubt if people at home are aware of the difficulties of designing a two-seater which one could pronounce, without hesitation, the best. It must have four major qualities: speed, climbing ability, diving speed, and handiness. The need of strength, or high factor of safety, goes without saying. Speed is simply a matter of power and head resistance, and is comparatively easy to attain alone; the rub comes in combining with it the requisite climbing power, and factor of safety. The Germans, in general, seem to believe in a very heavy, substantial motor, which cuts their climbing to a certain extent, but gives them a very fast dive. The Allies' machines, I should say, are slightly faster climbers, but cannot follow a diving Hun. And so it goes--to have one quality in perfection, another must be sacrificed. Last of all come the single-seaters, whose sole purpose is to fight. Many different types have been tried--monoplanes, biplanes, and triplanes, with different kinds of fixed and rotary motors. At present the biplane seems to have it (though I have seen an experimental monoplane that is a terror), as the monoplane is by nature too weak, and the triplane (magnificent otherwise!) is too slow in diving for either attack or escape. The work the different groups perform seems to be roughly the same in the Allied and enemy armies. The day-bombers fly at great heights, sometimes escorted and protected by single-seaters. The night-bombers fly fairly low, never escorted. Photographers, observers, and artillery regulators have a nasty job, as they must fly rather low, constantly subjected to a galling attention from old Archibald. When their mission requires it, they are escorted by chasse machines--a job that single-seater pilots do not pine for, because they often go twenty or thirty miles into "Bochie," where motor-trouble means a soup diet till the end of the war; and because, at low altitudes, hovering over a slow "cuckoo," the anti-aircraft gunners have too good a time.