LIGHTNING.
Lightning is only the discharge of a Leyden jar on the grand scale, upon which Nature performs her operations. Two clouds charged with opposite electricities, and separated by the non-conducting air, approach each other. When the tension becomes sufficient to overcome the resistance, the two forces rush together with a blinding flash and terrific peal. The lightning moves along the line where there is the least resistance, and so describes a zig-zag course. If we can trace the entire length, we call it chain lightning; if we only see the flash through intervening clouds, it is sheet lightening ; and if it is the reflection of distant discharges, we term it heat lightning. The report of thunder is caused by the clashing of the atoms of displaced air. The rolling of the thunder is produced by the reflection of the sound from distant clouds. Sometimes the clouds and the earth become charged with opposite electricities, separated by the nonconducting air.
G. GOODCHILD.
FLIGHT.
For hundreds of years men have tried to emulate the feats of birds, and fly, and therefore most of them based their ideas on ornithoptors, or machines that fly by flapping wings, like a bird. They overlooked the fact that a very large portion of a bird's body is devoted to the muscles that work the wings, and that a man's physical power was not a quarter as powerful as it needed to be.
Many men were killed during experiments with gliding, and artificial wings, such as Oliver of Malmesbury, 1065 ; Otto Lilienthal, 1896; and Percy Pilcher, 1899. ' But all these men helped in some way or another in the conquest of the air.
It was on the 17th of December, 1903, that Wilbur and Orville Wright flew in an aeroplane of the design of the present-day one, the flights ranging from 12 to 59 seconds.
But after that the design of the aeroplane increased very rapidly, only six years passing before Bleriot flew the Channel from Barraques, near Calais, to Dover, in 1909, and ten years later, in 1919, the first direct Atlantic crossing was made by Alcock and Brown, in a Vickers Vimy standard military bombing machine, with two Rolls Royce engines, thus winning the greatly coveted record for Britain.