Whileat12milesthesustainingpowerisfiguredat230pounds，at24milesitisfourtimesasgreat，or920
pounds.
SupportingAreaofBirds.
Oneofthethingswhichallproducingaviatorsseektocopyisthemotivepowerofbirds，particularlyintheirrelationtotheareaofsupport.Closeinvestigationhasestablishedthefactthatthelargerthebirdthelessistherelativeareaofsupportrequiredtosecureagivenresult.Thisisshowninthefollowingtable：
SupportingWeightSurfaceHorseareaBirdinlbs.insq.feetpowerperlb.