The Aurora Borealis.Many persons who witnessed the Aurora on Friday morning last, aud many who heard of the phenoineonu,have aafred,and will ask the question, what is the cause of such an appearence. While freely admitting that it is much easier to ask questions than to satisfactorily answer them, we may state that it is a generally admitted opinion that those lights are caused by electricity in elevated portions of the atmosphere. All extensive bright iights or luminous clouds iu the northern hemisphere of the heavens, *vhen seen at night, are called the Aurora Borealis. The hues of this light frequently vary, and have lines of white, blue, purple, green, red, yellow,and other colors and shades of colors. These varying colors are caused by the electic light passing through different densities of air. It is stated that the most ran-lied air produces a white light; the most dry air, red; and the most clamp produces yellow streaks.Many theories, aud some of them very plausible, have beeu advanced to explain the cause of the Aurora. The theory of sun light passing through the earth, a through Sims’ hole in the earth, has had its day of believers; and others might be stated. It is, however, now very generally admitted that the Aurora Borealis is an electric light. Electricity pervades all matter throughout creation, and although a subtle aud invisible fluid, is yet as powerful as it is all pervading.