These jumps served still further to develop the ability of the men to control the machine and perfect their balance, and it gave them the first sensation of being in flight at high speed, though not high enough to do any great damage should one of them be so unlucky as to smash up. A smash-up was what we particularly wished to guard against at all times, not only because of the cost of repairs and the delay, but largely because an accident, even though it may do no injury to the aviator, may seriously effect his nerves. I have known of beginners who, while making rapid progress in learning to fly, suffered a complete setback just because of an unimportant accident to the machine in flight, or in landing. Eagerness to fly too soon is responsible for many of the accidents that befall beginners. An ambitious young man may become thoroughly convinced after a few jumps that all he needs for making a long and successful flight is the opportunity to get up a hundred feet or so. The first chance he has, he goes up as he had planned, and unless he is lucky or an exceptionally quick thinker, the odds are that he will smash up in getting back to earth again. I have never seen any one more eager to fly, and to fly as quickly as possible, than were these officers. Probably they were following the military bent of their minds or, perhaps, it was the enthusiasm of the pioneer in a new science. As a rule, the mornings at San Diego are fine. There is seldom any wind during the forenoon, except when one of the winter rain storms blows in from the ocean. We tried to get in as much work during this calm period as possible. The mornings were found to be the best for doing this work. It was most desirable, not to say necessary, that the pupils should have a minimum of wind during their early practice work. Even the lightest wind may sometimes give serious trouble to the beginner. A gust may lift the aeroplane suddenly and then just as suddenly die out, allowing the machine, should it be in flight, to drop as quickly as it rose. Such a moment is a critical one for an inexperienced man. He feels himself dropping and unless he keeps his head clear, he may come to grief through doing too much or too little to restore his equilibrium. In the practice work all the officers, as well as two private students, C. C. Witmer of Chicago and E. H. St. Henry of San Francisco, used the same machine. This was one of the older types of biplane, with especially strong wheels, and with a four-cylinder engine. This type was selected as best adapted to the strain of heavy work. It had sufficient power, under its regular equipment, to fly well, but had not the very high speed of the latest type, fitted with eight-cylinder engines. For beginners, I consider the four-cylinder machines the best.