6oo 



NA TURE 



[October 20. 1923 



Republic of Salvador and Guatemala : archaeological 

 studies at the Mesa Verde National Park, Colorado, 

 and of totem poles in Alaska. Less generously 

 endowed scientific institutions in Great Britain will 

 look with envy on such enterprises, but will recognise 

 them with full appreciation as important additions to 

 the general stock of human knowledge. 



The Rede lecture for 1923, by Prof. H. A. Lorentz, 

 on " Clerk Maxwell's Electromagnetic Theory " Is 

 to be issued in pamphlet form in November by the 

 Cambridge University Press, 



Messrs. D.ulau and Co., Ltd., 34 Margaret Street, 

 W.I, have just circulated a useful catalogue (No. 105) 

 of second-hand books on entomology, general zoology, 

 geology, and mining. Nearly 2000 works are listed, 

 and the prices asked appear very reasonable. 



Messrs. Ernest Benn have in their autumn list 

 several books of scientific interest, among which we 

 notice " The Principles and Practice of Wireless Trans- 

 mission," by Parr, in which the theory of the pro- 

 duction and control of wireless waves is set forth in 

 non-technical language ; " Across the Great Crater- 

 land to the Congo," by A. Bams ; " The Diseases 

 of Glasshouse Plants," by Dr. W. F. Bewley, of the 

 Cheshunt Experimental Station, giving the practical 

 results of the experimental work of the station in 

 recent years ; " Successful Spray mg," by P. J. 

 Fryer, which is primarily intended as a handbook for 

 the practical grower wishing to know the results of 

 recent researches upon the subject ; " An Introduc- 

 tion to the Study of Chinese Sculpture," by L. 



Ashton, which professes to be the first European 

 book dealing with this branch of Chinese art ; and 

 " Plastic Art in China," by O, Siren, with an intro- 

 duction and epigraphic notes by P. Pelliot. , 



Prof. W. E. Dalby is bringing out, through? 

 Messrs, Edward Arnold and Co., " Strength and 

 Structure of Steel and other Metals," the main 

 purpose of which is to correlate strength of metal 

 with their structure. In this volume the subject 

 has been considered from the point of view of the 

 engineer, and, so far as possible, in terms readily 

 understood by the engineer. Other books in the 

 same publishers' announcement list are : " A Hand 

 book of the Coniferae and Ginkgoaceae." by W. Dalli 

 more and A. B. Jackson, containing descriptions in 

 easily understood terms of all the cone-bearing trees, 

 with information upon their economic uses an! 

 cultivation. Although the book is primarily 1 

 general wofk upon conifers, special attention ha 

 been given to those that are hardy in the British Isles 

 or are of outstanding economic importance. A 

 feature of the work is the series of keys to genera 

 and species which are designed to assist beginners 

 in the work of identification. " British Hymenop- 

 tera," by A. S. Buckhurst, L. N. Staniland, and G. B. 

 Watson, with an introduction by Prof. H. Maxwell 

 Lefroy, being an introduction to the study of the 

 habits and life-histories of British saw-flies, wood- 

 wasps, gall-flies, ichneumon-flies, ruby-wasps, digger- 

 wasps, mud-wasps, wasps, bees, and ants. Informa- 

 tion is given as to their identification, and technical 

 terms are carefully explained. 



Our Astronomical Column. 



The Want of Symmetry in Stellar Velocities. 

 — Proc, Nat. Acad, of Sciences, U.S.A., for September 

 contains an article by Dr. G. Stromberg, of Mt. 

 Wilson, on this subject. This unsymmetncal dis- 

 tribution was first found by B. Boss from a study of 

 measures of parallax and radial velocities ; later 

 Adams and Joy found it independently. Stars of 

 high speed appear to move towards the hemisphere 

 between galactic longitudes 160° and 340° (through 

 250°). 



Dr. Stromberg extends the research to the globular 

 clusters and spiral nebulae, finding that all known 

 objects appear to show the same asymmetry ; he 

 conjectures that it may arise from the existence of 

 a fundamental system of reference, with regard to 

 which excessive velocities are very infrequent. The 

 stars of moderate velocity were found to be divisible 

 into two groups, one with a slightly eccentric velocity- 

 ellipse in the galactic plane, the other with a more 

 eccentric ellipse. 



The stars of high velocity give an ellipse with axes 

 parallel to the last ellipse, while the globular clusters 

 and spiral nebulae give circular distribution : in each 

 case the group-motion increases pari passu with the 

 internal motions. On the assumption that the spiral 

 nebulae have acquired the maximum attainable 

 velocity, he calculates the position of the fundamental 

 frame, and shows that referred to it the sun is moving 

 with velocity 651 km. /sec. towards R.A, 305°, N. Decl. 

 75°. 



New Transit Instrument at Paris. — M. B. 

 Baillaud, director of the Paris Observatory, describes 



NO. 2816, VOL. I 12] 



in the Comptes rendus of the Paris Academy of 

 Sciences for August 7, a new transit instrument 

 which has been erected at the Observatory for the 

 determination of the time that is distributed by wire- 

 less signals from the Eiffel Tower. These signals are 

 now used so widely that the question of their degree 

 of accuracy is important to many astronomers ; hence 

 an instrument was designed of such a size that it 

 could be reversed on every star. The object glass is 

 by M. Viennet, and is of excellent quality ; its ap>er- 

 ture is 4 in. and focal length 48 in. The magnifying 

 power is 60 ; the self -registering micrometer has two 

 threads that travel in opposite directions at the same 

 rate, crossing each other at the centre of the field. 

 The threads are driven by electric motor and the rate 

 of driving is regulated by a rheostat. The object of 

 the two threads is to save the time required to get 

 the star on the tliread again after reversal ; haN-ing 

 been observed on one thread up to reversal, it is 

 automatically found very close to the other after 

 reversal. The order of positions is reversed for 

 alternate stars. 



The level error is found both by spirit levels and by 

 nadir observations. The coUimation error is at pre- 

 sent determined on the nadir, but collimators are in 

 course of erection. 



The results of time determination are satisfactorj-. 

 The figures that are printed never show a greater 

 range for separate stars on the same night than 

 a tenth of a second ; it seldom exceeds half of this 

 amount. 



