VOL. XVI.] PHILOSOPHICAL TRANSACTIONS. 37 J 



of intermediate objects between the eye and the object. For then the imagi- 

 nation must allow room for all these things. Hence it is, that if we see a thing 

 over two hills, between which there lies a great valley unseen, it will appear 

 much nearer than if we see the valley also, and it will appear as just beyond the 

 first hill. And if we move forward to the top of the nearest hill, so that the 

 valley may be seen, it will then appear much farther off than before. And on 

 this account it is, that the sun setting, appears to us as if it were but just be- 

 yond the utmost of our visible horizon, because all between that and the sun is 

 not seen. And, on the same account, the heaven itself seems contiguous to 

 the visible horizon. 



Now when the sun or moon is near the horizon, there is a prospect of hills 

 and valleys, of plains, woods, rivers, and a variety of fields and inclosures, 

 between it and us ; which present to our imagination a great distance capable 

 of receiving all these. Or, if it so happen that in some position these inter- 

 mediates are not actually seen ; yet having been accustomed to see them, the 

 memory suggests to us a view as large as is the visible horizon. But when the 

 sun or moon is in a higher position, we see nothing between us and them, 

 unless perhaps some clouds, and therefore nothing to present to our imagination 

 so great a distance as the other is. And therefore, though both be seen under 

 the same angle, they do not appear to the imagination of the same magnitude 

 because not both fancied at the same distances, but that near the horizon is 

 judged larger, because supposed farther off, than the same when at a greater 

 altitude. 



It is true, that as to small and middling distances, beside this estimate from 

 intermediates, the eye has a faculty within itself to make some estimate of the 

 distance. As, when we already know the size of a thing seen, to which we 

 have been accustomed, as a man, a tree, a house, or the like ; if such thing 

 appear to us under a small angle, and indistinct and faintly coloured, the ima- 

 gination allows such distance as to make the thing so to appear. And if 

 this through a prospective glass be represented to us under a larger angle, and 

 more distinct, it is accordingly apprehended as so much nearer. But the case 

 is otherwise when we do not, by the known magnitude, judge the distance; but, 

 by the supposed distance, judge of the magnitude, as in the case before us. 

 And accordingly different persons, according to different fancied distances, 

 judge very differently. As, if two stars be showed to ignorant persons, and 

 you ask how far they seem to be asunder, one perhaps will say, a foot : another 

 a yard, or more ; and one shall say, the sun appears to him as large as a bushel, 

 another, as large as a Holland cheese ; each estimating according to the fancied 

 distance. Again, in our two eyes, when the object is seen by both, there is 



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