434 



NATURE 



[June 26, 1913 



cannot be used in contact with air, but in an enclosed 

 vessel (protected by a current of purified air whenever 

 it is opened) the rise of conductivity is only 0-004 

 gemmho per hour in contact with clean electrodes, or 

 001 gemmho in contact with electrodes that have 

 recently been used for dilute salt-solutions. The value 

 of this new development in measuring the conductivity 

 of very dilute solutions is too obvious to require 

 further emphasis. 



The second number has reached us of a new 

 periodical, Zeitschrift fiir Betonbau, dedicated to the 

 science of construction in reinforced concrete ; it con- 

 tains descriptions of various works carried out in this 

 material, besides theoretical investigations from various 

 engineers. The most novel feature of this number 

 is a description of a swimming bath 25 metres long 

 and !2 metres wide, containing 510 tons of water. 

 This is supported on three points on the top of low 

 piers, and is housed in a large building, the con- 

 struction of which is described. A large bridge near 

 Pressburg, with one span of 30 metres and another 

 of 18-40, is described, and the computations of bending 

 moments and reactions leading to the determination 

 of the necessary reinforcement are set out very fully. 

 The character of this paper bears ample testimony 

 to the thorough manner in which Austrian and Ger- 

 man engineers are taking up the designs of structures 

 in this material. 



Engineering for June 20 contains an illustrated 

 account of the Hamburg-Amerika liner Imperator. 

 This vessel left the mouth of the Elbe on Wednesday, 

 June 11, for her first regular voyage. Her dimensions 

 are approximately 50,000 tons register, 880 ft. in 

 length, 98 ft. in beam, and 63 ft. in depth from main 

 deck to keel. The depth from the upper boat-deck to 

 keel is 101 ft. 8 in. The Vaterland was launched 

 recently for the same company, and a third sister 

 vessel is on the stocks; these vessels will be only 

 slightly greater than the Imperator. The horse-power 

 of the latter is 62,000, derived from Parsons turbines, 

 and the speed is 22-5 knots. The vessel is equipped 

 with eighty-three boats, sufficient for 5500 people, 

 i.e. 300 more than she will carry, counting both 

 passengers and crew. The boat-lowering gear is very 

 complete ; there is one electric motor on the boat-deck 

 for every three boats, and there are special arrange- 

 ments for maintaining horizontal the boat while being 

 lowered. In addition to the commodore, the ship 

 carries four captains, who have commanded large 

 steamers successfully, and one of these will be always 

 on watch, while the fourth takes general control of 

 the crew. 



The Cambridge University Press has arranged for 

 the issue of a series of volumes under the general title 

 ,,f 'The Cambridge Psychological Library," to be 

 edited by Dr. C. S. Myers, University lecturer in 

 .-xperimental psychology and director of the psycho- 

 logical laboratory. Among the volumes already 

 arranged are :— " Psychology," Prof. James Ward; 

 'The Nervous System," Prof. C. S. Sherrington, 

 F.R.S. ; "The Structure of the Nervous System and 

 the Sense Organs," Prof. G. Elliott Smith, F.R.S. ; 

 NO. 2278, VOL. 91] 



"Psychology in Relation to Theory of Knowledge," 

 Prof. G. F. Stout; "Mental Measurement," Dr. W. 

 Brown; and "Collective Psychology," Mr. \Y. 

 McDougall, F.R.S. 



Messrs. Joiix Wheldon and Co. have just issued 

 an ornithological catalogue containing titles and other 

 particulars of more than 1500 books and papers, and 

 including selections from the libraries of several 

 eminent ornithologists. 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences for July: — 

 July 1. I5h. 26m. Saturn in conjunction with the 



Moon (Saturn 6° 30' S.). 

 3. i6h. 0111. Venus at greatest elongation 



west of the Sun. 

 5. 3I1. om. Jupiter at opposition to the Sun. 

 ,, I3h. 39m. Mercury in conjunction with the 



Moon (Mercury 3 49' S.). 

 7. 3I1. om. Mercury at greatest elongation 



east. 

 16. 15b. 29m. Jupiter in conjunction with the 



Moon (Jupiter 4 47' N.). 

 18. 1311. om. Neptune in conjunction with the 



Sun. 

 ,, I3h. 49m. Uranus in conjunction with the 



Moon (Uranus 3 24' N.). 



20. 6h. om. Mercury stationary. 



21. I2h. 52m. Venus in conjunction with 



Saturn (Venus i° 18' S.). 



28. 3I1. 12m. Mars in conjunction with the 



Moon (Mars 5 41' S.). 

 ,, 2oh. om. Uranus at opposition to the Sun. 



29. 6h. 12m. Saturn in conjunction with the 



Moon (Saturn 6° 42' S.). 

 ,, 19!]. 30m. Venus in conjunction with the 

 Moon (Venus 7 40' S.). 



Minor Planets. — The April number (vol. ix., No. i>) 

 of The Soutli African journal of Science contains an 

 article by Mr. Robert T. A. Innes, entitled "The Minor 

 Planet MT. 191 1 : and on Minor Planets in General." 

 The Union Observatory at Johannesburg devotes a 

 considerable portion of its time to these small bodies, 

 and the work it does is shown in relation to the minor 

 planet problem in general. This article will be found 

 of particular interest to those whose astronomical 

 work lies in other directions, for Mr. Innes writes 

 generally on the subject of these bodies, and particu- 

 larly of MT. 191 1. To mention one or two points of 

 prominent interest, he states that in 1S93 no minor 

 planet would be given a permanent number until five 

 observations were available, but to-day such a number 

 is not allotted until observations spread over six 

 weeks are available, and a satisfactory orbit is com- 

 puted. Reference is made to Eros, to the nearly 

 simultaneous publication of Sir David Gill's result of 

 the solar parallax determination from observations of 

 the minor planets Victoria, Iris, and Sappho, the 

 value he obtained being S802" ±0-005", and to Hinks's 

 value of 8-806" ±0004" from his fine Eros work. Dr. 

 Metcalf's method of minor planet search, that of 

 guiding the telescope so that the plate remains approxi- 

 mately at rest with regard to the usual motion of the 

 minor planet while the stars trail, is mentioned, and 

 numerous other important items, such as the different 

 groups of minor planets, the arrangements for 

 organised effort, the discovery of Palisa's MT. iqii, 

 and its subsequent rediscovery. 



Cordoba Catalogue of 5701 Stars. — Dr. C. D. 

 Perrine, in the twentieth volume of the Results of the 



