132 



NATURE 



{Dec. 1 1, 1879 



information on the subject. In the islands of St. Christopher and 

 Nevis, which form part of the division of islands commonly 

 called the Lesser Antilles, monkeys are found in large numbers, 

 and a planter friend in the former island, which I have recently 

 visited, assured me that he had lately been obliged to appoint a 

 " monkey- watchman " to protect the cane-fields and the sweet- 

 potato fields of his estate from the destructive raids of bands of 

 monkeys. 



In the island of Nevis, which at one time must have formed 

 part of St. Christopher, and which is now only divided from the 

 latter by a very narrow arm of the sea, appropriately called 

 " The Narrows," monkeys — -the same as those of St. Christopher 

 — exist in great numbers, and I may add that the tails are " per- 

 fectly prehensile," i.e., "naked beneath towards the tip." 



Of Trinidad I cannot speak from personal observation, but a 

 scientific friend of mine, Dr. H. A. Alford Nicholls, who lately 

 visited Trinidad, kindly writes to me as follows: — "Prof. 

 Mivart has certainly made a mistake about there being no 

 monkeys in the West Indies. I find, too, that in a work on 

 ' Central America, the West Indies, and South America,' edited 

 by the traveller, Bates, it is stated that there are no monkeys in 

 the Antilles. You know more of the monkeys of St. Kitts and 

 Nevis than I do, but I can tell you something of your Trinidad 

 cousins. There are two kinds of monkeys in Trinidad, and as 

 the fauna is continental, they will doubtless be found on the 

 mainland of South America. One belongs to the Mycetes, and 

 it is called the Red Howler, partly on account of its loud and 

 hideous cries ; the other, a diminutive specimen of the Cebida;, 

 is called the ' Sapajou ; ' it is a Cebus." 



I shall be glad to supply any further information on the sub- 

 ject of monkeys in St. Christopher and Nevis. 



Dominica, British West India, Edmund Watt 



November II 



Earthquakes in Iceland 



Ix Nature, vol. xxi. p. 89, I see the earthquake which 

 occurred in Iceland on September 24 last ascribed to "volcanic 

 eruptions in the Krisuvik Mountains, a locality where eruptions 

 have not been known within the memory of the present genera- 

 tion." The use of the word " eruption " here is misleading, for 

 though the earthquakes, which frequently occur at Krisuvik, are 

 no doubt caused by volcanic action, nothing of the nature of an 

 eruption, in the usual sense of the word, has been known to 

 occur there within the historical period. The boiling springs, 

 mud caldrons, and sulphur deposits, for which Krisuvik is noted, 

 are, on the authority of Prof. Bunsen (Letters to Berzelius), to 

 be ascribed to a pseudo-volcanic action occurring at compara- 

 tively slight depths. Though slight earthquake shocks have 

 frequently occurred, during the last eighteen months, while I was 

 at Krisuvik, I have never observed that they had any effect on 

 the boiling springs and other thermal phenomena. 



The earthquake of September 24 last, though more violent 

 than any other which I have experienced there, differed from the 

 rest in no other respect. They are generally confined to the 

 neighbourhood of the hot springs and sulphur beds, though the 

 last was felt over a wider area, and seldom do any damage. 



Edinburgh, December 1 W. G. S fence Paterson 



Diatoms in London Clay 



I do not know if diatoms have been observed in the London 

 clay, or not. If they have not, it may interest many to know 

 that 1 have discovered triangular, quadrangular, elliptical, and 

 discoidal forms in the London clay ol Sheppey. The frustules 

 are frequently perfect, and the markings are plainly discernible 

 as square sided depressions or elevations ; I am not certain 

 which. One of the discoidal forms is an old friend, for I ob- 

 served it in abundance two years ago ; but as I then had no 

 knowledge of diatoms, I passed large quantities by as pyritous 

 concretions. 



In my ignorance I stated in a paper on the well referred to 

 (Proc. Geol. Assoc, vol. v. p. 357) : " It should be mentioned 

 that at and below 293 feet the clay was thickly studded with 

 very minute disks of iron pyrites, each having a boss in the 

 centre, and the edge slightly turned up all round. They were 

 uniformly perfect, as much so as if cast in one mould." 



A few days ago I saw Anlico.liscus oreganns, and was struck 

 by its resemblance to the disks I had seen in the London clay. 

 As I had not preserved any of these, I set to work to get more, 



if possible, and last night I was fortunate enough to find several 

 distinct species. w. H. Shrudsole 



62, High Street, Sheernesson-Sea, December 2 



Colour-Blindness 



The remarks of Mr. Everett at the close of his paper (Nature, 

 vol. xxi. p. 62) on Prof. Hering' s theory, seem to be founded on 

 a misconception. Prof. Hering assumes, not four, but six 

 elements of colour sensations connected by the equations — 

 B -f W=&R + C = off + V = o. 



The specification of any colour in his system contains there 

 independent variables, and is of the form 



D = a U r + B R + cb, 

 and it will usually take four equations to eliminate W R and B. 



It must be noted that Prof. Hering assumes that the red- 

 green and blue-yellow sensations never occur in nature pure, but 

 always mixed with white. If this is granted I do not think that 

 the result of Maxwell's experiments on colour-mixture will be 

 found inconsistent with his theory. JOHN TENNAxr 



19, The Boltons, S.W., November 2S 



Intellect in Brutes 



I offer the following illustrations of reasoning powers in 

 animals, should you care to insert them. 



1. Some years since, while hunting in Northern Michigan, I 

 tried, with the aid of a professional trapper, to entrap a fox who 

 made nightly visits to a spot where the entrails of a deer had 

 been thrown. 



Although we tried every expedient that suggested itself to us, 

 we were unsuccessful, and, what seemed very singular, we always 

 found the empty trap sprung. 



My companion insisted that the animal dug beneath it, and 

 putting his paw beneath the jaw, pushed down the pan with 

 safety to himself; but though the appearances seemed to. confirm 

 it, I could hardly credit his explanation. This year in another 

 locality of the same region, an old and experienced trapper 

 assured me of its correctness, and said in confirmation, that he 

 had several times caught them, after they had made two or three 

 successful attempts to spring the trap, by the simple expedient 

 of setting it upside down, when, of course, the act of undermining 

 and touching the pan would bring the paw within the grasp of 

 the jaws. 



2. A Dandie Dinmont terrier, after the death of his mistress, 

 was playing with some children in a room into which was brought 

 a photograph (large) of her, that he had never previously seen. 

 It was placed upon the floor leaning against the wall. In the 

 words of my informant, who witnessed it, the dog, when he 

 suddenly caught sight of the picture, "crouched and trembled all 

 over, his whole body quivering. Then he crept along the floor 

 till he reached it, and, seating himself before it, began to bark 

 loudly, as if he would say, 'Why don't you speak to me?'" 

 The picture was moved to other parts of the room, and he 

 followed, seating himself before it and repeating his barking. 



3. The dog whose demoralisation by the salute of a monkey 

 was published in Naturf, vol. xviii. p. 77, recently had another 

 encounter with one, and behaved in so sneaking a manner as 

 showed that he had not forgotten his first impression. 



Boston, November 22 C F. Crehore 



Electric Lighting 

 In Nature, vol. xx. p. 641, you say, "For the first time 

 perhaps in the history of electric lighting two rival magneto- 

 electric machines are illuminating the same hall." I can state 

 an earlier instance, though not an exact parallel. At the annual 

 fair of the American Institute, held in New York during 

 September, October, and November, 1S7S, the main ball v. as 

 illuminated by the Wallace-Farmer machine and light, and the 

 machinery hall— directly communicating with it, by the Brush 

 apparatus. The two halls form practically one. 



Alex. s. Gibson 

 Norwalk, Conn., U.S.A., November 14 



JEAN BAPTISTE ALPHONSE CHEVALLIER 



THE death is recorded on December 1 of Prof. A. 

 Chev.illier, who deserves notice here as one of the 

 Nestors of French pharmaceutical chemistry. He was 



