KNOV/LEDGE 



[JcLT 24, 1885. 



absorption Leing probably co: 

 have then to compare two 

 an apparent surface equal to l-700th of the sun's 

 and of an averasfe intrinsic lustre equal to one- 

 fifth of his ; the other from an apparent surface corre- 

 sponding to two-thirds of a ring around the earth's disc, 

 about two and a half miles in width and of only l-20th 

 the sun's intrinsic lustre. Now the apparent size of this 

 ring round the earth, as seen from the moon, has been 

 shown (see Knowledge for April 2i, 1885, p. 341) to be 

 l-889th of the sun's apparent disc. Hence the ratio we 



1 1 1 



1 



5334 : 700, i.e., nearly 8 to 1. 



Yet ^ 



we have seen that along rRr', Fig. 4, or 1' from 

 the edge of the geometrical shadow, the eye recognises 

 so great a loss of light that the shadow seems to occupy 

 the space r S r' ; how little then can any part of the 

 shadow w^ithin s S s' he affected by the small modicum of 

 refracted light which can fall there, even under condi- 

 tions rather more favourable than usually exist. 



I have not thought it necessary so far to take special 

 account of the action of the higher layers of the air, in 

 bringing light within the geometrical shadow. This 

 action has to be considered in two aspects. In the first 



place it increases, so far as it is effective at all compiared 

 with direct light from the sun, the amount of light 

 falling outside s S s' Fig. 4. For so soon as the sun even 

 begins to pass behind the earth, as seen from the moon, 

 refraction is at work in bringing the geometrically 

 hidden parts of his disc into view. But such parts must 

 necessarily be intensely flatte)ied — so to speak, and the 

 amount of light reaching the moon through such refrac- 

 tive action must always be very small compared with 

 that which arrives directly, so long as any part of the 

 sun's face remains unconcealed (geometrically) by the 

 earth. 



Suppose, for instance, three-fourths of the sun's diameter 

 covered, geometrically. Then the sun as seen from the 

 moon would be wholly visible, in the shape shown in 

 Fig. 5, the part really behind the earth being compressed 

 into a thin zone along e E e', the inner edge of this zone 

 being raised a mile or so above the earth s true outline. 

 (It would only reach this when the sun had passed so far 

 into the shadow that only actual grazing refraction would 

 bring him into view.) Beyond e and e' would be two 

 fine arcs of light extending to h and V, where lines from 

 C the centre of the earth's .shadow touch the disc of the 

 sun. The centre of the sun being about 8' below (or 

 rather within) E would be raised into view by the action 

 of that layer of air which for an observer on earth would 

 produce a horizontal refractive of 4', about one eighth of 

 the horizontal refraction at the sea-level. This would 



correspond to an elevation of about 11| miles. The 

 atmosphere 14 miles above the sea-level would bring up 

 only about 4' of sun breadth ; the atmosphere 17| miles 

 high only about 2'. Now it takes a depth of nearly 70 

 miles of our atmosphere to subtend 1' at the moon's dis- 

 tance. So that the zone bringing any appreciable 

 amount of refracted light, would be very narrow indeed. 

 Probably I am far within the truth in saying tliat if 

 the sun had just set geometrically Leliiml the e;irth, 

 while the part of his disc farthest in wnuM ;ii.|M;Lr nl.out 

 three-quarters of a mile above the sea-Ievcl, the |.:irt ju.st 

 within (geometrically) would not be apparently raised 

 more than twenty miles above the sea-level by the refrac- 

 tive action of that portion of the air effective in bringing 

 it into view. The illumination derived from the 

 meniscus arc of light so showing would be very small 

 compared with full sunlight — possibly about l-10,000th 

 part on the average. In colour it would be but slightly 

 tinged with red, under ordinary conditions, — so slightly 

 that probably by comparison with partsof the moon further 

 within the earth's geometrical shadow, illuminated by 

 ruddier light, this portion would look slightly bluish. It 

 would be a very narrow zone of shadow, however. 



THOUGHT AND LANGUAGE. 



By Ada S. Ballin. 



"\T7E have seen that the deaf-mute thinks -.aA reasons 

 W and finds a means for expressin.' Iji^ i ieuu'lirs ; 

 but we have not yet touched upon tlie (jin >t !■ n ■■{ l,,jv) 

 he thinks. The questio- r^f tl>e m^rr. r in whieli thought 

 proceeds is one of gri .•■'"• ! • it is one to which 

 very little attention i- i ■ . : \ ] sychologists. If 



an intelligent and \v( ii-i 'ii:e:i:i i ]iei-.s(in, with all his 

 senses intact, is asked tlie itsual fcrin of his thoughts, he 

 will generally be at a loss what to answer, and this arises 

 from the fact that, as a rule, we think, but are not con- 

 scious of the act of thinking, and pay no attention to it. 

 If, however, we do turn our attention inwards we find 

 that for the most part we think in imaginary sounds. 

 As Goethe says, man is a creattu-e of custom : — 



Aus der Gemeine ist der Mensch 



Und die Gewohnheit nennt er seine Amme. 



"We are so accustomed to express our thoughts in certain 

 varied groups of sounds which we call words, that wo 

 chiefly think, as it were, in suppressed sounds or words. 

 It is this fact that led to the conftision of thought with 

 speech among the ancients, who held that thought and 

 speech are identical, except that thought " is the un- 

 uttered conversation of the soul with itself, and that 

 the stream of thought which flows through the lips and 

 is audible is called speech," according to Plato's summary 

 of the matter in the " Sophist." 



If we look closely into the question we find that 

 thought and language are by no means identical, although 

 so closely associated by habit. For example, the same 

 thought may be expressed in half-a-dozen different ways, 

 and we select that which seems most suitable to us, while 

 at other times r. thought presents itself to the mind 

 and we find the greatest possible difiBculty in clothing it 

 with words. Further, while all nations have to a great 

 extent the same thoughts, each has a different way of 

 expressing them. I have previously compared words to 

 coins which take the place of articles alike cumbrotis for 

 transportation or storage ; and, in fact, they are handy 



