November i8, 1920] 



NATURE 



387 



has been caused by the spreading of bracken on good 

 pasture lands, and it is possible that by utilising the 

 rhizomes for animal food the infested areas can be 

 cleared without incurring much loss. 



The October issue of the Journal of the American 

 Chemical Society contains a long paper by Mr. VV. D. 

 Harkins on the structure of atoms. Evidence is given 

 for the statement that atoms in which the ratio of 

 negative to positive electrons in the nucleus is high 

 are rare, both in meteorites and on the earth. Sug- 

 gested constitutions are assigned to the nuclei of the 

 more abundant light atoms. The constituents of 

 atoms are regarded as a-particles, positive electrons 

 (hydrogen nuclei), electrons, particles of mass 3 

 (v-particles), and secondary structures of positive and 

 negative electrons (/i-particles). 



Engineering for November 5 contains an illustrated 

 account of a large depdt to be used for the storage of 

 wool, now approaching completion at Hull. This 

 building is being constructed for the Ministry of 



.Munitions by Messrs. Nissens, Ltd., of Birmingham, 

 and is a development of the well-known Nissen hut, 

 which proved its practical utility on a wide scale so 

 successfully during the war. The area covered is 

 approximately 10 acres, and construction was com- 

 menced onlv on June 16 last. The depdt consists of 

 eighteen buildings of the Nissen type, each 552 ft. 

 long bv 40 ft. wide, all communicating. Each semi- 

 circular rib is made up of five segments joined by 

 fish-plates ; the ribs are held together by wood purlins. 

 The buildings are double-skinned, with an air-space 

 of 7 in. between the inner and outer linings of gal- 

 vanised corrugated sheet, and are thus damp-proof 

 and not affected by condensation. Only forty 

 men, on piecework, have been employed, and the 

 rate of building has been approximately one bay of 

 552 ft. completed per week. The form of construction 

 has several advantages, and is suitable for many 

 purposes. Buildings of practically any length can be 

 made ; they are absolutely weather-proof, are capable 

 of erection by unskilled labour, and if lined with 2-in. 

 plaster slabs will be found as cool as brick buildings. 



Our Astronomical Column. 



The Eclipse of i<)J2 in .Australia. — Further details 

 concerning this eclipse have come to hand. Mr. \V. E. 

 Cooke, the Government Astronomer of New South 

 Wales, has visited various points on the Queensland 

 railway within the totality track, and sends a pamphlet 

 containing his experiences. The inhabitants of the 

 villages are willing to give all possible help to 

 observers. The weather prospects are distinctly 

 hopeful, though the altitude of the sun in this region 

 will not be great (26° at most). The most easterly 

 and most accessible station is Stanthorpe, on the 

 Dividing Range, 2656 ft. high, a favourite summer 

 resort, having several good hotels. Those undertaking 

 observations of a delicate nature should go further 

 inland, to Coongoola or Goondiwindi. As there is a 

 branch of the British .Astronomical .Association in New- 

 South Wales, there is reason to hope that all these 

 stations will be occupied. The west coast of .Australia 

 in the neighbourhood of Condon or Wallal is favour- 

 able as regards heijfht of sun and probability of a clear 

 sky. Mr. H. .A. Hunt, the Commonwealth Meteoro- 

 logist, notes that Wallal, which is a telegraph station, 

 might be reached from Port Hedland, 150 miles to the 

 west-south-west by pearling lugger; a steamer visits 

 Port Hedland about once a month. Mr. Hunt con- 

 siders the weather prospects much more hopeful here 

 than in Christmas Island. .Another possible locality 

 1» in Central .Australia, near the telegraph station of 

 Charlotte Waters, which is no miles from the head of 

 the railway at Codnadatta. 



Iipitkr's Satellites.— Mr. R. T. .\. Innes has 



rried out a regular series of observations of the 



lipscs of these satellites, especiallv of I. and II., 



lire iqcS; he gives the main results in Union Obs. 



< ire. No. 50. On comparing the observed duration 



"f eclipse with the tabular value, there is a regular 



M.nve m the residuals with a six-year period, from 



'A hirh it is inferred that the tabular inclination of 



ipiter's equator to its orbit needs a positive cor- 



' tion ; it is indicated with less certainty that the 



lie of the equator on the orbit needs a negative 



rrection. The tabular values of mean longitude 



■ epoch need the following corrections: I., -o-o8o°; 



NO, 2664, vol.. 106] 



11., — ooji°; and 111., -0006°: These results are 

 of interest, and they show that the idea, so generally 

 held, that ordinary visual observations of these eclipses 

 are no longer of use, is not correct. 



.Mr. Innes appeals to all observers to unite in ob- 

 serving the eclipses with special care for the period 

 1920 December 9 to 1921 May 31. The month 

 February 18 to March 18 may be omitted, as eclipses 

 then take place very near the primary. The disappear- 

 ance of the last speck of light and the re-appearance 

 of the first speck are the phenomena to which atten- 

 tion should be specially directed. The aperture and 

 condition of seeing should be noted. .Mr. Innes points 

 out that observations of satellite I. afford a delicate 

 test of the constancy or otherwise of the earth's 

 rotation. 



The Okigi.n ok Spectra.— Dr. H. II. Plaskett con- 

 tributes an interesting article on spectra to the Journal 

 of the Royal .Astronomical Society of Canada (vol. xiv., 

 p. 7). The paper summarises Nicholson's work on the 

 atom and that of Planck and Einstein on the quantum 

 theory of light. It is pointed out that there are some 

 serious difficulties in the quantum theory. " Interfer- 

 ence can be obtained with a path-difference of more 

 than a million wave-lengths. This seems to require 

 that the quantum must have this length (several feet) 

 in space. Further, the exp<'rimental fact that a 3.ft. 

 O.G. has a higher resolving power than a 3-in. can 

 only be interpreted as meaning that the quantum has 

 a 3-ft. cross-seetion.. It is difficult to see how a 

 quantum of such dimensions is indivisible, and if it 

 is, how any light gels into a 3-in. telescope." It is 

 suggested that the facts seem to require some com- 

 promise between the undulatory and quantum theories ; 

 m fact, the author considers a salisfaclorv theorv of 

 radiation as the first desideratum of future progress, 

 the second being a solution of the three.body problem 

 as applied to the more complex atoms. 



Dr. .Silberstein's suj*cestion that the atomic nucleus 

 may not be a homogeneous sphere of positive elec- 

 tricity, but a collection of point charges, is shown to 

 remove some difficulties, hut to create others, which 

 have not vet been solved. 



