48o 



NATURE 



{April i8. 1872 



the land ; and by thus misleading Sir John Herschel he has by 

 a coup de plume doubled all our continents. 



1. In the first volume of his " Asie Centrale," p. 165, writing 

 on " la hauteur moyenne des continents," Humboldt says, "en 

 cherchant a evaluer I'elevation moyenne de la hauteur des divers 

 continents, c'est a dire la position du centre de gravite du volump 

 des terres clevees audessus du niveau actuel des eaux. . . ." 

 It thus appears that Humboldt used the words " hauteur mo- 

 yenne," and " hauteur du centre de gravite du volume," as 

 equivalent expressions, vehich I submit they are not. Had he 

 said "centre de gravite de la surface," he would have been 

 right, for that height is the mean height. 



2. But though inaccurate in expression, Humboldt could never 

 be other than right in principle. Fortunately in the " Asie 

 Centrale " he describes with much detail the process by which 

 he arrives at his so-called "centre de gravite du volume" ; and the 

 process legitimately leads to the mean height. He divides the 

 continent into great areas, which I shall call a-^, a.,, a., . . . 

 finds the mean height of each /'i, /'.,, ^3, . . . by taking the 

 mean of several ; and then the mean height is 



a ^ li-^ + a^b„ + g;) ^3 ■ ■ . 



(7i + flj + (73 . . . 



A range of mountains he regards as a triangular prism ; and 

 to find its mass he multiplies tlie area of the base by half the 

 mem height, and then computes how much this would raise the 

 whole country if spread over it ; and the former number thus in- 

 creased i>, as is plain, the mean height. 



3. Arago, in his " Astronomie Populaire," cites the labours of 

 Humboldt with approbation, goes over all the details, adds a 

 vast number more, and deduces numbers approximately the 

 same for the mean height of land. Arago, it is to be observed, 

 invariably uses the phrase " hauteur moyenne." Lilce Humboldt, 

 he considers that the mean of all the continents lies between goo 

 and 1,000 feet. 



4. Humboldt (Note 360, " Cosmos ") apologises for differing 

 from La Place, who, he says, made the mean height of conti- 

 nents iiion- than three titites too great. Now La Place's estimate 

 was 3,078 feet. 



I conclude, therefore, with the greatest deference, that Hum- 

 boldt's "centre de gravite du volume" is an inaccurate ex- 

 pression, and that he meant "centre de gravite de la surface," or 

 mean height. If this be so. Sir John Herschel has jbeen led 

 into the error of doubhng our continents, which he estimates 

 at a mean elevation of 1,800 feet. 



It is a matter of some importance ; for Sir Charles Lyell 

 computes that the continent of N. America will be utterly 

 washed away into the ocean by the ordinary processes of de- 

 gradation in four and a half millions of years. If, indeed, 

 this period is to be doubled, we can take a more cheerful 

 view of the future of that continent. But I greatly fear with 

 Sir Charles thit it is limited to four and a half «iillions of 

 years, unless some upheaval of the land shall protect its short 

 span of existence. JoH.N Carrick Moore 



113, Eaton Square, March 28 



Conscious Mimicry 



The idea of mimicry in animals being induced through the 

 sense of sight appears to me to deserve more than a passing 

 notice of M. G. Pouchet's statement that changes of colour in 

 prawns, to accommodate them to the colour of surrounding 

 objects, are prevented by removing the eyes of the prawns. 



In 1869 I expressed my belief that such was the case, and 

 endeavoured to embrace a large class of phenomena, as well as 

 mimicry, withm the same instrumentality. I allude to the 

 asserted cases of the human or other fojtus being affected through 

 the sense of sight of the mother. But on ascertaining the views 

 of many able medical men, as well as of scientific naturalists, 

 I found opinions so divided on the matter that I did not think it 

 desirable to pursue further inquiries, nor publish my memoranda 

 made at the time. I could not bring myself to see that natural 

 selection alone could produce mimicry. If it were of rare 

 occurrence it would be called a remarkable coincidence, and 

 might reasonably be due to selection, but what is really very 

 general becomes a law, and must be traced to some far more 

 "regular " influence than nitural selection. 



In basing the idea of mimicry in general upon the supposed 

 act of the fcetas being susceptible through the mother's sense of 



sight, one is aware of the critical nature of the ground adopted, 

 and that possibly nine-tenths of the cases recorded must be put 

 aside as worthless ; but I have stronj reasoas for believing the 

 one- tenth at least to have been true. 



On the other hand, the experiments of Mr. Leslie on the 

 caterpillars of Poiitia Kapee, which when enclosed, some in black 

 and others in white boxes, produced chrysalises respectively 

 modified to suit the colour of the box ySe. Gossip, 1867. p. 261), 

 appeir to support my view, as also do those of Mr. Robert 

 Holland (/l>. p. 279), in which the cocoons of the Emperor 

 moth spun in white paper were white, while those on soil or in 

 dead grass were brown. G. IIenslow 



The Adamites 



Mr. C. Stanil^ni) Waice objects to my remarks on his paper 

 on the "Adamites," which paper he protes's is "written at least 

 in a truly scientific spirit." This, I venture to say, is just Mr. 

 Wake's error. He does not seem to be aware that comparative 

 phdology has a scientific method, and that words have to be 

 compared by sound and structure according to fixed and even 

 strict principles. Mr. Wake comes upon a Sanscrit word pi/ci, 

 father, and finds in it a primitive root ta, which he compares 

 with another syllable ta got by cutting in two in the same way 

 an Arabic verb, 'ata. Had he looked into the structure of San- 

 scrit, he would have found that pita is the nominative case, and 

 precisely the one that does not show the real crude-form of the 

 word, which is pitai; the tar being a suffix. If it is lawful to 

 compare languages by cutting words up anyhow and finding re- 

 semblances among the bits, of course connections may be found 

 between any languages whatsoever. In the same easy way Mr. 

 Wake finds a relation in Polynesian myth dogy between a divine 

 being called Taata (by the way, he should have taken the name 

 in one of its fuller forms, such as Tamata or Tangata), and 

 another divine being called Tiki. But these are two different 

 gods with different attributes, why should their names be altered 

 to make them into one ? 



Mr. Wake thinks it nonsense for me to have set up an imaginary 

 derivation for Paddy and Taffy, as commemorating the same 

 ancestor Ad or Ta, from whom he traces Akkad and Taata. But 

 of all ways of testing methods, one of the most useful is to try 

 whether they can be made to prove transparent nonsense. If 

 they can, it is evident that the method wants correction. As for 

 my communication to you being anonymous, it was so for much 

 the same reason that .\Ir. Wake's name was not mentioned in it, 

 viz. , that it is best to keep the personal element in the background 

 in such matters, and the paper itself is the thing to be judged by. 



M. A. I. 



If your correspondent, " M. A. I.," instead of endeavouring 

 to negative the conclusions of Mr. Wake's paper "by such 

 nonsense as the reference to Paddy and Taffy," as the author of 

 the paper justly observes, had brought forward the word Adam 

 itself, and shown that, by dividing it into .Id and am, and prefix- 

 ing its consonant in each case, we obtain Dad and Mam, father 

 and mother, he might have been held to have been critical, as 

 well as satirical. 



I believe, however, that Mr. Wake is wholly wrong in his 

 conclusions, simply because his premisses are wholly wrong. 



The word Adam has nothing of the meaning oi father in it. 

 The Ad, which Mr. Wake has so ingeniously made so much of, 

 should for his argument be the Hebrew Ab, Arabic .4lia, a 

 father. To suppose that the word Adam has anything of the 

 meaning of y;;//;tv- in it shows a complete disregard of its root- 

 meaning. In Hebrew the verb adam means he was red or broken, 

 and the substantive .4dam means a red or a brrani man. The 

 word Edom is from the same root, and means the Red land, pro- 

 bably because Red Sandstone constitutes its principal geological 

 formation, and even adamah, the ground, is so called because of 

 its reddish or dark brown colour. The Scripture narrative of the 

 origin of man is that the Creator formed " the Adam (or man) 

 of the dust of the adamah (or ground)." 



If Mr. Wake's object had been to show that the Adamites 

 were derived from the earih ox earth-horn, he would have found 

 little difficulty both by internal and external evidence ; he might 

 have instanced the autochthones of the Greeks, the homines 

 (humus, the ground), of the Latins, the yellow-eartli men of the 

 Chinese, and the red-clay men of the North American Indians. 



April IS Bi G. Jenkins 



