394 



NATURE 



[September 21, 191 1 



THE ASTRONOMICAL AND ASTROPHYSICAL 



SOCIETY OF AMERICA. 1 

 ("\KIGINATING on the occasion of the formal opening 

 of the Yerkes Observatory in October, 1897, the 

 Astronomical and Astrophysical Society of America now 

 includes in its membership most of the workers in 

 astronomy and allied subjects throughout the Western 

 Continent, and many from other countries. Inaugurated 

 for the purpose of advancing astronomy and astrophysics, 

 its system has been to hold an annual meeting of the 

 nature of a conference, lasting for several days, generally 

 at a different location each year. Accounts of the meetings, 

 with abstracts of the various papers presented, have been 

 published from vear to year either in The Astrophysical 

 Journal or in Science. At the tenth annual meeting, held 

 at Verkes, August, 1907, the publication of the present 

 volume of proceedings was authorised, and its preparation 

 entrusted to Prof. W. J. Hussey, of the Detroit Observa- 

 tory at Ann Arbor, Michigan. It contains full particulars 

 of the organisation of the society, and abstracts of the 

 papers presented at all the meetings ; the majority of these 

 are now well known, and being only short summaries are 

 not suitable for further abstraction. 



The society undertakes the organisation of special 

 branches of astronomical investigation, in a similar manner 

 to the various sections of the British Astronomical Associa- 

 tion. One of the most important of these deals with the 

 collection of data referring to meteors, and it has strongly 

 recommended the establishment of a network of photo- 

 graphic stations about one hundred miles apart for the 

 purpose of obtaining a record as complete as possible of 

 all the meteors appearing within the network. Automatic 

 instruments of as simple and inexpensive type as can be 

 obtained are recommended. 



Another section deals with cometary phenomena, and the 

 society financed a special expedition to Honolulu for the 

 photographic recording of Halley's Comet in May, iqio, in 

 charge of F. Ellerman, of the Mount Wilson Observatory. 



In a report of progress on the radial velocity determina- 

 tions at the Lick Observatory, W. W. Campbell mentions 

 that the programmes of observation for the Mills spectro- 

 graph attached to the 36-ir.ch equatorial, and for the 

 D. O. Mills expedition to Santiago, Chile, have aimed to 

 secure at least four spectrograms of every star down to 

 50 visual magnitude, with three-prism dispersion if 

 possible, and of fainter stars with two-prism dispersion. 

 Up to June 1, 1907, three-prism spectrograms of 882 stars 

 had been obtained at Mount Hamilton. It was expected 

 that the programme would be completed by June, 19 10. 

 On the D. O. Mills expeditions Messrs. Wright and Curtis 

 have obtained 530 stars brighter than 501 visual magni- 

 tude, and 150 stars fainter than 5.00 magnitude. The 

 total number of separate stars the spectra of which have 

 been photographed is 1368. Many new spectroscopic 

 binaries have been discovered during the progress of the 

 reductions, but it has only been possible to investigate fully 

 th. orbits of a few of the total number now known. 



Charles P. Butler. 



COAST-SURVEYING.- 

 T N surveying, uniformity of method may be carried to a 

 point at which it militates against maximum efficiency, 

 which demands that each region should be surveyed by the 

 method most suited to its character and the object in view. 

 While a uniform method of operations facilitates the com- 

 pilation of results, a reasonable adaptation of method to 

 the case in hand distinguishes a scientific survey from a 

 mechanical process of measurement. 



Dr. Ball has been engaged for several seasons in survey- 

 ing the eastern desert of Egypt, including both the mining 

 area and the Red Sea coast, carrying on a triangulation of 

 approximately second-order and a plane-table topographical 

 survey at the same time. In aiming at th' 

 economy of time, together with adequate accuracy, he has 



1 Publications of the Astronomical and Astrophysical Society of America. 

 ' 1 ganisation, Membership, and Abstracts of Papers, 1897-1905. 

 Pp. Kxvii4-347- (Ann Arbor. Michigan : The Society, 1910.) 



: "A New Method of Coast. surveying." By Dr. !- Hall. Survey 

 Department Paper, No. 11. (Cairo, iqn.t 



NO. 2 1 86, VOL. 87] 



employed the tin thod described in this paper along the 

 coast of the Red Sea. Having fixed by triangulation a 

 series of points on moderately high ground overlooking the 

 coastal plain, he determines a series of points on the sea- 

 margin by observing their directions and the depression- 

 angles with a theodolite. Thus the azimuths of the lines 

 are obtained from that of a side of the triangulation, and 

 the determined altitude of the observation point furnishes, 

 with the depression-angle, the distance of the sea-margin. 

 So far the method is not new ; but the computations in- 

 volved are troublesome, and this has prevented the more 

 general use of it. 



To surmount this difficulty Dr. Ball uses a scale, to be 

 specially constructed by the surveyor for each station 

 occupied, such that when the apparent angle of depression 

 to a point on the coast is observed tli' scale will enable 

 the true distance of the point from the station to be at 

 once laid down on the chart. The height of the station 

 being accurately known from the triangulation, the 

 distances corresponding to the different depression-angles 

 can be computed for each 5' and laid off to scale without 

 any great expenditure of time. When a large extent of 

 coastline is to be mapped on a single scale, and numerous 

 stations will be occupied, it will be more economical to 

 construct a single-scale diagram, from which any desired 

 scale can be taken ; instances of such a diagram for both 

 metric and British units are given. 



This method should greatly facilitate the work of a 

 miiviU'i ongaged on a coast survey who thoroughly under- 

 stands the use of his theodolite and is possessed of adequate 

 neatness and accuracy in drawing. The accuracy of the 

 method is fully discussed, and the limits of distance for 

 which it can be employed are investigated on the assump- 

 tion that distances shall be correct to within 100 metres, 

 while the altitude of the station is not more than 1 metre 

 in error, the error of depression-angle does not exceed 10", 

 and the coefficient of refraction is liable to a variation not 

 exceeding 20 per cent, of itself. This study was under- 

 taken by Mr. H. E. Hurst, of the Survey Department, and 

 the whole memoir forms a very thorough piece of work and 

 an instructive addition to field-surveving. 



H. G. L. 



T 



WORK OF A LONDON NATURAL HISTORY 

 SOCIETY. 1 



HE South London Entomological and Natural History 

 Society has existed since 1872, and now numbers 

 169 members, many of whom are among the most 

 prominent entomologists of the day. The volume of publi- 

 cations before us is well printed and illustrated, and as it 

 is not likely to be so widely circulated as it deserves, it 

 may be well to give a detailed list of the various interest- 

 ing papers included in it. 



Robert Adkin, " On the Lepidoptera of a London 

 Garden." Discusses the conversion of the country 

 village of Lewisham into a suburban district, and the 

 resuits of thirty years' experience of what was, entomo- 

 logically, an actually barren plot of ground when laid out 

 as a garden. During this time, about 1S0 species cf 

 butterflies and moths, out of the British list of about 2000, 

 were obtained, of which eleven were butterflies. Among 

 these is Celastrina argiolns, which appears to have been 

 common at Lewisham in Stainton's time, and is still 

 a common garden insect at Chiswick, in quite a different 

 part of London. No great rarities are enumerated, but 

 this was perhaps hardly to be expected; on the other hand, 

 a largo number of species are mentioned as having been 

 only taken or observed once. 



Robert Adkin, " Notes on Hepialus hamuli and its Shet- 

 land forms." The writer considers that the form thulensis 

 is restrictr, 1 to" Shetland. Alfred Sich, "Larval Legs." 

 Deals with their development in certain Lepidoptera. 

 H. J. Turner, " A few days with the butterflies of Zer- 

 matt." Account of a collecting tour. Alfred Sich, "The 

 Middlesex home of Clausilia biplicata." Notes on the 

 t, 1 occurrence of this and othei land-shells in a locality 



1 Proceedings of the South London Entomological and Natural History 

 iel . 1 Utes. Pp. xvi + 175. (London: The Society, 



Hibernia Chambers, London Bridge, SI... n.d.) Price 4*. 6rf. 



