HERSCHEL, WILLIAM.

On Nebulous Stars, properly so called.

London, Lockyer Davis, and Peter Elmsly, 1791.. 4to. In recent marbled paper wrappers. Extracted from "Philosophical Transactions", vol. 91, read February 10, 1791. Including title-page of volume. Leaves reinforced in margin. (2), 91-88 pp.

First appearance of Herschel's seminal paper in which he stated: "The nature of planetary nebulae, which has hitherto been involved in much darkness, may now be explained with some degree of satisfaction, since the uniform and very considerable brightness of their apparent disk accords remarkably well with a much condensed, luminous fluid; whereas to suppose them to consist of clustering stars will not so completely account for the milkiness or soft tint of thir light, to produce which it would be required for that condensation of the stars should carried to an almost inconceivable degree of accumulation." (From the present paper).

Order-nr.: 58510