5i8 



NA TURE 



[April I, 1886 



despatch them to China. The harvest is during the months of 

 March and April. As soon as the nests are built, and before 

 the swallows begin to lay their eggs, they are collected ; the 

 birds then build second nests, and these are likewise taken away ; 

 the third nests are left undisturbed for the birds to lay and hatch. 

 The island visited by the Danish writer was abDut 500 feet 

 high, and 3000 feet in diameter. The caves are only accessible 

 by means of rattan ladder.s, and the nests are collected from the 

 roofs by means of rattan galleries and stagings. To show the 

 impossibility of ingress and egress without artificial assistance, 

 it is stated that about forty years ago, before the collection and 

 sale of the nests was made a Government monopoly, about fifty 

 Malays arrived at the caves before the Siamese, and commenced 

 taking the nests ; while they were engaged in this the Siamese 

 arrived, and in revenge ran away with the rattan ladders, 

 leaving the whole of the Malays to die of hunger and thirst in 

 the caves, from which their only means of escape had been 

 taken. Their skeletons are still in the caves. These Siamese 

 caves appear smaller, not so well ordered, and infinitely wilder 

 and more dangerous than those at Gomanton, but otherwise 

 there appears little difference in the nests themselves, cr in the 

 mode of collecting them. 



The latest numbers of the Ceylon OticntaUst (Nos. 3 and 4, 

 vol. ii.) are largely occupied with folk-lore. The editor writes 

 on comparative folk-lore, showing how certain Singalese stories 

 occur elsewhere in Sanskrit and Siamese collections. Mr. 

 Lewis's " Notes on some Oriental Folk-lore Stories " is on 

 much the same lines, the field e.\amined being somewhat more 

 extensive. Thus a story from a Singalese collection of stories, 

 the "Jataka," is found in English in Chaucer's "Pardoner's 

 Tale." There are two other papers of a like character. The 

 Rev. H. Horsley writes on Tamil proverbs, while Mr. Lewi-; 

 concludes some interesting papers on a subject which appears to 

 have escaped investigation hitherto— viz. the terms of relation- 

 ship in Singalese and Tamil. 



Prof. Lodge wishes to state that in his letter under the 

 heading of "Permanent Magnetic Polarity," in our last issue, 

 in the last paragraph the word "explained" should be " uii- 

 explained." 



The additions to the Zoological Society's Gardens during the 

 past week include a Ring-tailed Lemur (Lemur caltd) from 

 Madagascar, presented by Mr. Alfred Best ; a Bonnet Monkey 

 (Macacus siniciis) from India, presented by Dr. E. Woakes ; a 

 Mountain Ka-Ka [Nesloi- notabilis) from New Zealand, presented 

 by Mr. James Ellis ; four Leopard Tortoises ( Testudo parda/is), 

 eleven Angulated Tortoises {Chersina an^ulata), an Areolated 

 Tortoise {Homoptts areolata), three Geometric Tortoises {Testudo 

 geomdriea), a Robben Island Snake {Coronella p/iacaruui), two 

 Infernal Snakes [Boodon iiifernaUs) from South Africa, pre- 

 sented by the Rev. G. II. R. Fisk, C M.Z.S. ; two Common 

 Boas (Boa constrictor) from South America, a West African 

 Python (Python seha) from West Africa, presented by Mr. Daniel 

 Nicols ; two Golden Plovers (Ckaradrius pluvialis), European, 

 a Sharp-nosed Crocodile (Crocodilus acutus) from Central 

 America, deposited ; three Wheatears (Saxicola cenant/ie), 

 British, purch.ased ; a White-fronted Lemur (Lemur albifrom), 

 born in the Gardens. 



OUR ASTRONOMICAL COLUMN 

 The Binary Star /3 Delphini.— In 1873 Burnham dis- 

 covered that the primary star of the well-known wide double- 

 star j8 Delphini was itself a very close double, and a few years' 

 observations sufficed to sho.v that it was a binary star in rapid 

 motion. As the companion star has now described over lSo° 

 of its apparent path, a fairly accurate approximation to the 

 elements of its orbit is possible. An attempt has accordingly 

 been made, first by Dubiago and more recently by Gore, to 



determine the orbit, with tolerably accordant results. The 

 former makes the period to be 26 '07 years, with perihelion pas- 

 sage at i8S2'i9 and semi-axis major o"'55. Gore finds the 

 |.)eriod to be 30'9i years, and fixes the periastron passage at 

 iSS2'25, with semi-axis major = o"'5i7. The observations are 

 fairly well represented by these elements, considering what a 

 close and difficult object the star is to measure. According to 

 Gore's elements the components were at their minimum dis- 

 tance, o"'l92, at the epoch iSyg'gi ; and during 1S79 Burnham 

 failed to elongate the star with the l8J-inch Dearborn refractor. 

 We hope that those double-star observers who possess suffi- 

 ciently powerful telescopes will not lose sight of this interesting 

 object. 



The Velocity of Light and the Solar Parallax. — 

 From two determinations of the velocity of light made by Prof. 

 Michelson (in 1879 ^"^1 in 1882), and from one made by himself 

 in 1882, Prof Newcomb concludes that the most probable value 

 of this physical constant, expressed in kilometres per second, 

 is 299860 ± 30. Adopting Nyren's value of the constant of 

 aberration from Pulkowa obf^ervations, viz. 20" '492, the corre- 

 sponding value of the solar parallax is 8"'794, taking the earth's 

 equatorial radius to be 637S'2 kilometres, as determined by Chark. 

 We may also draw attention to the circumstance that Prof. New- 

 comb considers that his observations negative the hypothesis 

 put forward by Messrs. Forbes and Young as to the existence of 

 a difference between the velocities of rays of different colours. 

 Had there been such a difference to anything like the extent 

 asserted by these physicists, it would have shown a well-marked 

 effect in Prof. Newcomb's apparatus. No trace, however, of 

 any such effect could be seen. Prof. Michelson has arrived at 

 similar conclusions as to the erroneous nature of the views 

 expressed by the Scotch experimenters, 



Fabry''s Comet. — The following ephemeris by Dr. H. 

 Oppenheim (Astr. Nach. No. 2712) is in continuation of that 

 given in Nature for 1S86 March 18 : — 



i386 



For Berlin Midnight 

 R.A. Decl. Log t 



Log i Bright- 



April 16 23 58 4$ 38 46-9 N. 9-8317 9-6825 118 

 iS o 13 47 37 53-4 9S417 9-6282 145 



20 O 33 27 36 24-0 9-8527 9-5686 181 

 22 O 58 58 33 58-3 9-8645 9-5043 230 



24 I 31 39 30 2-6 9'877o 9-4370 297 



26 2 12 8 23 52-1 9-8S99 9-3726 376 



28 2 59 25 14 52-2 9-9031 9-3229 445 



30 3 50 o 3 37-0 N. 9-9165 9-3042 456 

 The brightness on December 2 is taken as unity. 



Barnard's Comet. — The following ephemeris by Dr. H. 

 Oppenheim (Astr. Nach. No. 2714) is from elements by Dr. A. 

 Krueger :— 



For Berlin Midnight 

 1886 R.A- Decl. Log r Log A Bright- 



h m. s. , , ness 



March 31 1 50 22 30 45-4N. 9-9509 0-2006 11 

 April 4 I 49 33 32 15 9 o-iS68 



S I 48 25 II 49-1 9-8776 0-1699 18 

 12 I 46 58 35 23-8 0-1494 



16 I 45 6 36 57-3 9-7962 0-I245 32 

 20 I 42 50 38 25-0 0-0)41 



24 I 40 23 39 3S-9 9-71SS 00568 62 

 28 I 38 22 40 260 001 II 



M.iy 2 I 38 8 40 28-4N. 9-6796 9-9556 118 

 The brightness on December 5 is taken as unity. 



The Nebula round Maia. — MM. Perrotin and ThoUon 

 (Comples rendus, cii., No. 10) have succeeded in seeing the Maia 

 nebula "without too much difficulty" ; but M. Perrotin adds, 

 " We have seen the nebula because we knew it existed. We 

 should certainly not have observed it else." The nebula seemed 

 comprised in an angle of about 120°, with the opening turned 

 towards the north-west, and the summit to Maia; one of the 

 sides lies along the line joining Maia to Bessel's star An. 4. 

 The general a|)pearance is that of a faintly luminous cloud, of 

 which the different parts are very unequally bright. A nebu- 

 lous filament stretching from Maia nearly to the little star just 

 named, and a region towards the north-east and nearly 2' from 

 Maia, are the brightest parts of the nebula. On one occasion 

 exceedingly faint luminous points were suspected in the centre 

 of this latter district. 



