The boys, who were now in their glory, had a portion of a small room in a wooden building assigned to them. At this time there were fifty machines of various types on the ground, the particular makes being the Bristol, the B. E., several Farman machines, and a half dozen Sopworth tractors. Tom Walton, the young American who greeted them at the hospital, was accorded the privilege of escorting the boys and introducing them. That they had been in the first battles of the war was sufficient to give them a coveted place in that company of enthusiastic men, for there was some glory in having been on a battlefield,--a thing which could have been said of only a few of those who entertained them that day. "I suppose you want to see the machines," said Tom. "Indeed, we do," said Alfred. "What is that big machine over there?" "That is a Bristol," answered Tom. "And there is another one," remarked Ralph, pointing to a machine, which was being drawn out of the hangar. "No, that's a B. E. biplane," answered Tom. "You will see the difference by observing the shape of the planes. The Bristol has the ends of the wings rounded so that the forward corners are cut away to a greater extent than the rear corners. In the B. E. the wings are cut to conform with the well-known Wright type." "That's a Farman machine, I know," said Ralph, pointing to an aeroplane which had a huge revolving type of motor forward of the main planes. "Yes; but when that machine is high in the air it would be difficult to recognize it from that description," said Tom. "You will notice that the lower plane is much shorter than the upper plane, and that it has a great spreading tail,--larger than any other machine now made." [Illustration: _Types of Allied Airplanes_] "Here is another kind, a little fellow. That certainly looks different from all the others," said Alfred, as they stopped in front of a hangar. "That's the Sopworth tractor, a fine, speedy machine, with square ends to the planes, and a heart-shaped tail. It can be distinguished at any altitude," answered Tom. "I notice that that has different tails," said Ralph. "Does that make any difference in the flying?" "Not in the least. Shape has nothing to do with it. Surface is all that counts. They are made with distinctive forms so that they may be easily distinguished, one from the other." "We saw some German airplanes, several dozens of them, in Belgium, and the only one I could recognize was the Taube, as they called it. They have fan-shaped tails," said Alfred. "But here is the machine for business," said Tom, as they halted in front of a gaily decorated hangar, and pointed to a trim little machine, which was being overhauled. "I see you have the Stars and Stripes above the door," said Ralph. "Yes; and this is my machine; isn't it a beauty?" said Tom with a considerable show of pride. "What is it? I mean what make?" asked Alfred.