Sept. 28, 1882] 



NATURE 



523 



Further it seems only just to add that, so early as March 27, 

 1871, Mr. Robert Louis Stevenson described to the Royal 

 Scottish Society of Arts forms of intermittent lighthouse appa- 

 ratus for exhibiting groups of flashes of occupations of unequal 

 period ; these arrangements, possessing the advantage over 

 Babbage's original proposal, that during dark intervals the light 

 is not simply stopped by a screen and thus lost, but sent usefully 

 in other directions to strengthen the bright intervals or flashes. 



William Swan 



Ardchapel, Dumbartonshire, September 21 



The August Meteors 

 As noted in NATURE, vol. xxvi. p. 37S, I observed a bright 

 display of meteors on the night of August 6, at Aberfeldy. On 

 the 7'h the sky was overcast with dense clouds all night j but on 

 the following night I saw a more brilliant shower of meteors 

 than on the 6th, with this difference that the meteors of the night 

 of the Sth were mostly ol several seconds' duration, and generally 

 left a long, bright train of light behind ; al.o, in place of being 

 on the north of the Milky Way, as on the 6th, they were chiefly 

 on the south of it. A very large and bright meteor burst out 

 ab)ut half way to the zenith, and moved nearly horizontally 

 from the south-east towards the west, leaving a long shining 

 streak behind, and lasting cl >se on fifty seconds. I watched the 

 meteors for the next three nights from the parish manse of Logie- 

 Almond, and witnessed on each night (9, 10, and 11) a gorgeous 

 shower. On the evening of the loth, before the twilight was 

 quite gone, I noticed thirteen very large meteors during the 

 space of a few minutes, although my view of the heavens was 

 very much intercepted by trees and by the manse. Between 



11 and 12 o'clock a meteor considerably larger and brighter than 

 \ enus under the m 1st In lurable circumstances, sailed over the 

 southern heavens, leaving a long train of light which lasted fully 

 a minute. Its position, time, and appearance, were nearly 

 the same as those of the large meteor I saw at Aberfeldy 

 on the night of the Sth. I have not for years, dining any 

 month, witnessed such a gorgeous display of meteors as I have 

 seen on the nights specified in August last. But I have scarcely 

 seen any since, except a few bright ones on Sunday night, 

 September 17, at High Blantyre. The display of the August 



was of a very short duration on each night, and after 



12 o'ebck not one scarcely could be seen. 



Govanhill, Glasgow, September 21 Donald Cameron 



ANIMAL INTELLIGENCE 1 

 1_7 ROM the time of Locke downwards the question, 

 ■*■ How far animals have the power of abstraction ? 

 has often been discussed. Locke himself maintained that 

 " the having of general ideas is that which puts a perfect 

 distinction betwixt man and brutes, and is an excellency 

 which the faculties of brutes do by no means attain to." 

 And this view is warmly advocated by Prof. Max Miiller 

 and other living thinkers. On the other hand Mr. 

 Romanes, who has made the subject of Animal Intelli- 

 gence a special study, writes : — ■" Give a cat or a dog 

 some kind of meat or cake which the animal has never 

 met with, and the careful examination which the morsel 

 undergoes before it is consigned to the mouth proves that 

 the animal has properly abstract ideas of sweet, bitter, 

 hot, nauseous, or in general, good for eating, and bad for 

 eating, i.e., abstract ideas of quality as apart from the 

 object examined— the motive of the examination clearly 

 being to ascertain which general idea of quality is 

 appropriate to the particular object examined." — Nature, 

 vol. xx., p. 123. 



Our first duty in a case like this is to make quite sure 

 of the meaning of the words we employ. Much con- 

 fusion may be, and has been, introduced into this subject 

 by a lax use of words. Let us consider, then, the several 

 meanings which these terms abstraction and abstract idea 

 may have. 



In the first place it seems to me that our most ordinary 

 impressions involve abstraction. An object is capable of 

 affecting us in a number of different ways, but of all 



■ From a Lecture delivered in Cape Town, South Africa. 



these at any given moment we onlv pay attention to one 

 or two which happen to interest us.' The re=t are practi- 

 cally non-existent for us. The mind automatically rejects 

 or eliminates them. This is certainly a process of ab- 

 straction, hut for the sake of clearness I venture to call 

 it elimination. By means of elimination we get definite 

 clear-cut mental impressions. 



In the second place our general conceptions involve 

 abstraction. A general conception is one which does not 

 stand for a particular object but for a group of objects. 

 It is arrived at by abstracting the essentials and neglect- 

 ing the unessentials. In the great number of dogs J see 

 around me, there are certain essential characters in the 

 midst of some diversities. As I consider them in the 

 mass, however, the diversities cancel each other in nn 

 mind, and I obtain a general conception of ad. 

 may for the purpose in hand call this process ;, 

 tion. The product is not a definite and clear-cut image. 



In the third place. I may by a process of abstraction 

 consider a quality apart from the things that possess that 

 quality— whiteness for example, apart fro n white objects, 

 edibility apart from edible things. We will here retain 

 the term abstract idea to denote such qualities, and we 

 will for the present term the process by which they are 

 obtained isolation. Of a completely isolated quality no 

 mental image can be formed. 



That dogs and the lower animals in general make use 

 of the process I have above termed elimination, cannot 

 I think, for one moment be doubted. For if they do not 

 then we must suppose that they are able mentally to 

 grasp an object in the entirety of its qualities, whic 

 more than the average human being can do. Let us 

 suppose that a dog sees what he believes to be a s 

 dog-biscuit. The impression he receives through 

 eyes at once suggests certain possible olfactory impres- 

 sions and certain possible gustatory impressions. This 

 of course implies what is commonly called the associa- 

 tion of ideas. But there are other possible impressions 

 which might be suggested but probably are not. 

 impressions, for instance, as may be produced by the 

 hardness, temperature, and weight of the object. Thes- 

 impressions are not suggested, they are eliminated, 

 speak. In other words, certain possible impressions are 

 abstracted from certain other possible impressions. Sup- 

 pose, now, the dog proceeds to smell the biscuit that he 

 has hitherto only seen. If it answers to his expectat : on = 

 he at once begins to eat it. His nose tells him that it is 

 good for eating. If, however, it does not answer to his 

 expectations, if, perhaps, it has received the drippin 

 a paraffin tin, he turns sorrowfully away. His nose tells 

 him that it is not good for eating. One kind of smell 

 suggests that the biscuit will be pleasant to the taste : 

 another kind of smell suggests that it it will be unpleasant 

 And the dog, unless he be a very young one. ha 

 confidence in his nose, acts upon the suggestions without 

 verification. It is to these suggested impressions that 

 Mr. Romanes applies the term "abstract ideas of qu 

 as apart from the object examined." And I do 

 suppose that any one is prepared to deny our dumb 

 companions abstract ideas in this sense oj the term. 



Let us now consider how far we may suppose animals 

 to possess the power of generalisation in the sense in which 

 I have above used this term. A dog lying asleep upon the 

 hearth-rug hears outside the window an unusual footstep. 

 He at once pricks up his ears and gives a half suppressed 

 growl. Must we not suppose that in such a case as this 

 the footstep suggests to the dog the idea of a strange 

 man? And if so, will not the suggestion— of whatever 

 character it might be — be general rather than particular ? 

 If it be a mental picture — and we are often told that dogs 

 think only in pictures ' — must not the picture be generic 



1 I do net know that I quite understand what thinking in pictures means, 

 but I should imagine that sounds and smells entered pretty largely into the 

 current of canine thought. And on the other hand, I should be disposed to 

 think that Spenser and Shakespeare possessed in no slight degree the power 



