Professor Ball tells us that in gaseous bodies the loss of heat involves a corresponding contraction of the volume, attended with a rise of temperature. To quote his words: “As the temperature of the mass increases the rate at which it parts with heat also increases. The contraction of the volume will proceed at an accelerated pace, and the temperature rise with increasing rapidity. Though the temperature of the gas may at first have been extremely low it will gradually rise until it becomes sufficiently high to render the gas visible by actual incandescence. As the process advances still further the body may pass from a mere nebula into a star-like object. With increase of contraction the pressure also increases and materials which were originally gaseous will assume more and more a density resembling that of solid bodies.” He says further that should the sun contract into a globe less its present size by one ten-thousandth part of its diameter it would amount to a shrinkage in its diameter of 87 miles. “But,” he continues, “on so mighty a globe this alteration is relatively insignificant; indeed no measurements that could be made at our observatories would be sufficiently delicate to detect a change of this magnitude. Helmholtz has, however, shown that if the sun were to undergo even this small diminution of volume the quantity of heat that would be thereby liberated for the purposes of radiation would supply the sun’s current rate of expenditure for nearly 2000 years. We have no means of knowing at present whether the actual contraction of the sun takes place at this rate or any other rate.”[3] Thus we see astronomers admit that a contraction of merely four miles of the sun’s diameter would be sufficient to supply its heat for a century, while a contraction of 87 miles, or 1/10,000 part of its diameter, would give to it heat for twenty centuries, were the sun gaseous. This being the case how is it possible to detect in this century, with a contraction of but four miles, whether the sun is growing either larger or smaller, or in any wise changing its volume? When its diameter was twice as large as now it must have been so much cooler that it moved more slowly and radiated less heat. With a diameter of 10 millions of miles, of 100, 1,000, 3,000, or 6,000 millions of miles even, and the sun then more years than it is now days in turning, can we suppose that it revolved swiftly enough to throw off rings; or, with a surface so expanded, was possessed of heat to any great amount? These are thoughts that should be carefully considered in looking at the theory of the formation of worlds from nebulae; for any explanations concerning the existence of a fire-mist so extensive as to reach Neptune’s bounds are of no small consideration, and should be open to careful scrutiny before absolute acceptance. [Illustration: Decoration] FOOTNOTES: [1] Warren. “Recreations in Astronomy,” p. 182.