Strato-Cumulus are dark globular masses of large clouds, often covering the whole heavens in the fall and the winter. They hang as low as 6,000 feet, and always predict changing weather. The lowest-hanging cloud of all is the Stratus, which is uniform at a height anywhere from 100 to 3,500 feet. It may be either drifting or stationary. It is a uniform layer, and resembles a fog, but, unlike the latter, it does not rest on the ground. The Nimbus is a thick layer of dark clouds with ragged edges but without shape. Rain or snow usually falls from this formation. There are many rifts in these clouds, and through them many higher clouds are seen. The Nimbus usually occupy altitudes from 300 to 6,500 feet. CHAPTER XII COMMERCIAL FLYING BUSINESS POSSIBILITIES OF THE AEROPLANE—SOME CELEBRATED AIR RECORDS—GERMANY’S INITIAL ADVANTAGE—A HUGE INVESTMENT—CAUSES OF ACCIDENTS—DISCOMFORTS OVERCOME—INEXPENSIVE FLYABOUTS—THE SPORTS TYPE—ARCTIC FLIGHT—NO EAST OR WEST In the face of the extraordinary development of the aeroplane and what it has accomplished in the Great War, both for the Hun and the Ally, it seems almost incredible that it was only as recent as December 17, 1903, that the Wright brothers made man’s first successful sustained and steered flight in a heavier-than-air machine driven by a gas-engine over the sand-dunes of Kitty Hawk, North Carolina! Upon that historic occasion Wilbur Wright flew 852 feet in fifty-nine seconds, and his four-cylinder gas-engine could generate only 12 horse-power!