276 



NATURE 



{Jan. 22, 1880 



fessors Hans and Lobwirmski respecting ideal matter of various 

 degrees. Can you inform me whether any English publications 

 have appeared on this subject, and if not, what foreign works 

 would be best suited to give an insight of the results that have 

 been arrived at to one who can devote but a limited time to such 

 investigations ? 



Surely the conclusion suggested by your correspondent (viz., 

 that the moon in its composition closely resembles caseine) is 

 intended only as a joke ; for, assuming the equation given, 



M = C m N n O p H q , 

 and even granting that the quantities m np q are in such propor- 

 tion as to make the right-hand member of the above equation 

 assume the form of the chemical formula for caseine, there is 

 surely no reason why the mass of the moon (which your corre- 

 spondent has chosen to denote by C) should be interpreted as 

 carbon, nor its direction of motion N as nitrogen, nor its velocity 

 O as oxygen. Percy R. Harrison 



Sun-Spots 



In the "Life of Charlemagne," written by Eginardus, one of 

 the Emperor's household, and afterwards Abbot of St. Bavon's, 

 in Ghent, occurs the following passage : — 



" Per tres continuos vitreque termino proximos aunos et solis 

 ct luna; creberriura defectio, ac in sole macula quredam atri 

 colons septem dierum spatio visa." 



' ' In three successive years nearest to his death [there were] very 

 frequent eclipses of the sun and moon, and in the sun there were 

 seen certain spots of a black colour, for the space of seven days." 



This life, written between S14 and S43, and referred toby the 

 writer's contemporaries, has been collated with several MSS. 

 by the Bollandists, who give it in full in their Acta Sanctorum 

 under January 28. It is a curious, if not a valuable, contribu- 

 tion to the early history of sun-spots, and suggests questions 

 which some of your correspondents may care to consider. 



Henry Bedford 



All Hallows College, Dublin, January 15 



A Clever Spider 



In a letter I have just received from my brother at Ronde- 

 bosch, near Cape Town, he narrates the following, which I 

 thought might interest some of the readers of Nature: — 



" On Friday I was much interested in watching a spider and 

 male glow-worm. The spider was a common long-legged house 

 spider who had a web in the corner of the room. It was an 

 aristocratic spider, in fact. Presently a male glow-worm flew 

 into the web, and in a few minutes the spider had wound him 

 round and round till no Egyptian mummy was more securely 

 housed. Just as this operation was being finished, a second 

 glow-worm Hew into the web, a long way from tin first. Off 

 goes the spider, and soon he, too, was encased in silk. Then I 

 noticed that the spider went three times backwards and forwards 

 between the head of glow-worm No. 2 and a main strand of his 

 web. After this he went round cutting all the threads around 

 the glow-worm until it hung by the head strands alone. The 

 spider then fixed a thread to the tad end, and by it dragged the 

 carcase in the direction of glow-worm No. 1 (presumably the 

 larder). As soon as the rope attached to the head was taut, the 

 spider made the rope he was pulling by fast to a strand of the 

 web, went back, cut the head ropes, attached himself to the 

 head, and pulled the body towards the larder, until the tail rope 

 was taut. In this way, by alternately cutting the head and tail 

 ropes and dragging the glow-worm bit by bit, he conveyed it to 

 the larder, where it hung alongs de mummy No. I. Another 

 presently flew in. After he was enwrapped in silk, the spider, 

 whether on purpose or not I cannot say, cut the last thread by 

 which he hung, and dropped him to the ground. Whether he 

 thought that this morsel might get ' high ' before he could eat 

 it I cannot say. I should say that the prey was some twenty 

 times the weight of the captor." Ll. A. Morgan 



St. Thomas's Hospital, Westminster, January 12 



Erratum in Paper on Tidal Friction 



An erratum has been pointed out to me in my article in 

 Nature, vol. xxi. p. 235, and I should be glad to correct it. 



The forty -second line of the second column of p. 236 runs : — 

 " so that the earth will rotate faster than the moon revolves." 



By a slip of the pen I here wrote "faster" instead of 

 "slower." G. H. Darwin 



January 16 



AFGHAN ETHNOLOGY 



'"PHE events now in progress on the north-western 

 ■*■ frontier of British India have for the third time in 

 this century directed the serious attention of statesmen, 

 historians, and ethnologists to the remarkable people 

 who give their name, or rather one of their names, to the 

 north-eastern division of the Iranian table-land. During 

 the empire of the Sassanides the whole of this region, 

 from Persia proper to the right bank of the Indus and 

 from the Koh-i-Baba, Ghor and other western continua- 

 tions of the Hindu-Kush to the Arabian Sea was known 

 as Khorasan, that is, Khoristan, the Land of the Sun or 

 the East. This term, with the gradual reduction of the 

 Persian sway, has shrunk to the proportions of a province 

 on the north-eastern frontier of the Shah's estates, and 

 has been replaced further east by the ethnical expressions 

 Afghanistan and Balochistan, the lands of the Afghans 

 and Baloches. But these expressions, as so frequently 

 happens, are so far misnomers and deceiving that the 

 lands in question harbour many other peoples besides 

 those from whom they are now named. In Balochistan, 

 for instance, the most numerous, powerful, and influential 

 element is not the Baloch at all, but the still unfathomed 

 Brahdi, from which circumstance it has even been 

 suggested that the country ought rather to be called 

 Brahuistan. A similar suggestion could not certainly 

 well be made with regard to Afghanistan, for here there 

 is no other people who can for a moment compare with 

 the Afghans in numbers or political importance. Still 

 the subjoined rough estimate of the population according 

 to nationalities will show that it is very far from being 

 homogeneous : — 



6, 145,000 1 



It will be noticed that in this table are included all the 

 races forming part of the present Afghan political system 

 taken in its widest sense, whose northern frontier is now 

 marked by the upper course of the Oxus. Before dealing 

 with the Afghans proper, with whom we are chiefly 

 concerned, a few words may be devoted to each of the 

 minor elements, all of whom continue to keep aloof from 

 their neighbours, seldom or never intermarrying, and 

 mostly retaining their own national customs, dress, 

 religion, and speech. No general amalgamation has, in 

 fact, yet taken place of these heterogeneous ingredients, 

 so that we cannot speak of the Afghan in the same sense 

 as we do of, for instance, the Italian, French, or English 

 nations. The Afghan race, though by far the most nume- 

 rous, has been politically predominant only since the death 

 of Nadir Shah (1747), and its rule has been far too 

 checquered by intestine strife and foreign troubles to have 

 allowed time or opportunity for the slow process of 



1 This figure exceeds by about a million that usually given as the total 

 population of Afghanistan. But recent exploration has shown that many of 

 the tribes are much more numerous than had been supposed, and as our 

 knowledge of the country increases, it will probably be found to contain 

 even a greater population than that here given. 



