Secondly, In foggy weather, at first sight, we generally imagine a small house, which is just at hand, to be a great castle at a distance; because it appears so dull and ill defined when seen through the Mist, that we refer it to a much greater distance than it really is at; and therefore, under the same Angle, we judge it to be much bigger. For, the near object _FE_, seen by the eye _ABD_, appears under the same Angle _GCH_, that the remote object _GHI_ does: and the rays _GFCN_ and _HECM_ crossing one another at _C_ in the pupil of the eye, limit the size of the picture _MN_ on the retina; which is the picture of the object _FE_, and if _FE_ were taken away, would be the picture of the object _GHI_, only worse defined; because _GHI_, being farther off, appears duller and fainter than _FE_ did. But if a Fog, as _KL_, comes between the eye and the object _FE_, it appears dull and ill defined like _GHI_; which causes our imagination to refer _FE_ to the greater distance _CH_, instead of the small distance _CE_ which it really is at. And consequently, as mis-judging the distance does not in the least diminish the Angle under which the object appears, the small hay-rick _FE_ seems to be as big as _GHI_. [Sidenote: Fig. IX. Why the Sun and Moon appear biggest in the Horizon.] 187. The Sun and Moon appear bigger in the Horizon than at any considerable height above it. These Luminaries, although at great distances from the Earth, appear floating, as it were, on the surface of our Atmosphere _HGFfeC_, a little way beyond the Clouds; of which, those about _F_, directly over our heads at _E_, are nearer us than those about _H_ or _e_ in the Horizon _HEe_. Therefore, when the Sun or Moon appear in the Horizon at _e_, they are not only seen in a part of the Sky which is really farther from us than if they were at any considerable Altitude, as about _f_; but they are also seen through a greater quantity of Air and Vapours at _e_ than at _f_. Here we have two concurring appearances which deceive our imagination, and cause us to refer the Sun and Moon to a greater distance at their rising or setting about _e_, than when they are considerably high as at _f_: first, their seeming to be on a part of the Atmosphere at _e_, which is really farther than _f_ from a spectator at _E_; and secondly, their being seen through a grosser medium when at _e_ than when at _f_; which, by rendering them dimmer, causes us to imagine them to be at a yet greater distance. And as, in both cases, they are seen[46] much under the same Angle, we naturally judge them to be biggest when they seem farthest from us; like the above-mentioned house § 186, seen from a higher ground, which shewed it to be farther off than it appeared from low ground; or the hay-rick, which appeared at a greater distance by means of an interposing Fog. [Sidenote: Their Diameters are not less on the Meridian than in the Horizon.]