If the man in the street is asked his opinion of the future of aviation, he will almost invariably reply, “ Everyone will have an aeroplane on his roof and go straight up like this.” Whereupon he will go through the traditional motion of the spiral staircase joke.

The expert pilot or technician of to-day, overhearing this remark, smiles in a superior way. In his mind are two contrasting pictures : That of a city over which whirligigs are springing up from adjacent roof tops; and that of the vast empty spaces of even the busiest airport as he knows it.