January, 1913. 



KNOWLEDGE. 



geometrical aspect of the question in its relation to 

 astronomy, as illustrated in Figure 7, where the 

 circle M may be allowed to 

 represent the moon, it is 

 clear that the portions of the 

 lunar surface at A and B are 

 seen under what we can 

 only describe as unnatural 

 conditions when viewed tele- 

 scopically from E, since they 

 would remain wholly invisible 

 to an observer capable of 

 inspecting the moon at close 

 quarters. Now, when we 

 apply a powerful telescope 

 and bring the moon appar- 

 ently nearer, as at m, the 

 portions of the lunar limb 

 at A and B remain visible, 

 instead of lying beyond our 

 sight at a and b, as the 

 figure shows the}- would do, 

 if we were in reality as near 

 the moon as the telescope 

 apparently brings us. It 

 follows that the lunar features 

 near the limb are always seen 

 under a certain amount of 

 distortion, which decreases 

 as we approach the centre 

 of the disc; but so familiar 

 has this telescopic deforma- 

 tion become, that the eve 



practically ignores it, and accepts the illusion of an 

 actually approxi- 

 mated moon. ^^^ 



Though a tele- 

 scope magnifying 

 onethousand times 

 is said to theoreti- 

 cally bring the 

 moon within a 

 distance of only 

 two hundred and 

 fort\- miles, we 

 must bear in mind 

 that an observer, 

 who might be 

 supposed to regard 

 our satellite at this 

 distance with the 

 naked eye, would 

 have a very differ- 

 ent scene present- 

 ed to his view from 

 that with which 

 telescopic astro- 

 nomy has made 

 him familiar. Not 



Figure 8. 



The Villa Fabbricotti, Florence, taken with a 



telephoto lens, magnifying 15 diameters, at a 



distance of .} mile. 



pur view. 



Figure 

 View of F'o-nce taken from the Palazzo Vecchio, and showing the 

 hills of Fiesole in the background. 



only would there 



be the geometrical reduction of the visible area 



under altered visual conditions, would wear a different 

 aspect. The astronomer's eyes, in fact, have become 



vitiated, so to speak, by this 

 peculiar action of the tele- 

 scope ; much as the musician 

 Complains that his ears have 

 become corrupted by accept- 

 ing the artificial intervals 

 brought intouniversal musical 

 practice by the adoption of 

 the system of tuning by equal 

 temperament. 



But if the eye, in accepting 

 the illusion of an approxi- 

 mated moon, has learned to 

 tolerate selenographical dis- 

 tortion, since it is solely under 

 telescopic conditions that 

 lunar detail has been brought 

 to our notice, the case is 

 quite another one when we 

 contemplate distant terres- 

 trial scenery through the 

 telescope. Here all is fam- 

 iliar, and the same, or at 

 least similar, objects have 

 been originally studied by 

 us at close quarters, so that 

 when we expect to witness 

 the anticipated approximat- 

 ing effect of our telescope 

 we stand amazed at the 

 curious spectacle offered to 

 In Figure 8, for instance, we notice to 

 some extent the 

 singular out -of - 

 drawing effect of 

 the ordinary tele- 

 photograph.' The 

 building illustrated 

 has an interest of 

 its own, being the 

 Villa Fabbricotti, 

 just outside the 

 gates of Florence, 

 where Queen 

 Victoria resided in 

 the spring of 1894; 

 while the photo- 

 graph, which was 

 taken with a tele- 

 photo lens magni- 

 fying fifteen dia- 

 meters atadistance 

 of a little over a 

 quarter of a mile, 

 shows, especially 

 on the right hand 

 side, in the seeming 

 divergence of the 



