It is further remarkable that in the newly discovered planets, of which the orbits are still more eccentric than that of Mercury, the masses are still smaller, so that the same provision is established in this case also. It does not appear that any mathematician has even attempted to point out a necessary connexion between the mass of a planet and the eccentricity of its orbit on any hypothesis. May we not then consider this combination of small masses with large eccentricities, so important to the purposes of the world, as a mark of provident care in the Creator? [19] The _eccentricity_ of a planet’s orbit is measured by taking the proportion of the _difference_ of the greatest and least distances from the sun, to the _sum_ of the same distances. Mercury’s greatest and least distances are as two and three; his eccentricity, therefore, is one-fifth. [20] The stability of the axis of rotation about which the earth revolves, has sometimes been adduced as an instance of preservative care. The stability, however, would follow necessarily, if the earth, or its superficial parts, were originally fluid; and that they were so is an opinion widely received, both among astronomers and geologists. The original fluidity of the earth is probably a circumstance depending upon the general scheme of creation; and cannot with propriety be considered with reference to one particular result. We shall therefore omit any further consideration of this argument. [21] Airy on Encke’s Comet, p. 1, note. [22] Principia, b. iii. prop. x. [23] Paley. [24] If the Laws of Motion are stated as _three_, which we conceive to be the true view of the subject, the other two, as applied in mechanical reasonings, are the following: _Second Law._ When a force acts on a body in motion, it produces the same effect as if the same force acted on a body at rest. _Third Law._ When a force of the nature of pressure produces motion, the velocity produced is proportional to the force, other things beings equal. [25] Though Friction is not concerned in any cosmical phenomena, we have thought this the proper place to introduce the consideration of it; since the contrast between the cases in which it does act, and those in which it does not, is best illustrated by a comparison of cosmical with terrestrial motions. [26] Butler, Serm. 3. [27] Müller, Infusoria, Preface. [28] _Monas._ Müller. Cuvier. [29] _Volvox._ [30] _Vibrio._ Müller. Cuvier. [31] Dupuis. Origine des Cultes. [32] Herschel on the Study of Nat. Phil. Art. 28. [33] Amici me cunctantem atque etiam reluctantem, retraxerunt, inter quos primus fuit Nicolaus Schonbergius, Cardinalis Capuanus, in omni genere literatum celebris; proximus ille vir mei amantissimus Tidemannus Gisius, episcopus Culmensis, sacrarum ut est et omnium bonarum literarum studiosissimus.--_De Revolutionibus. Præf. ad Paulum III._ [34] Lib. i. cx. [35] Pensées, Art. viii. 1. [36] Thomson’s Hist. of Chemistry, vol. i. 321.