It was no easy task.  In the first place, they wished the route to be as close to the equator at all times as possible, so that their line of travel would approximate in distance the world's estimated circumference of 24,899 miles.  In the second place, for stops they must choose cities or towns with either established landing-fields, or with grounds level enough for this purpose.  In the third place, these airports must be so divided that they would not have to be visited during the hours of darkness, for few if any of them would be likely to have efficient enough lighting systems to make night landings safe.