312 SCIENCE PROGRESS 



search department Dr. Silberstein has been working. They are the pubUshers 

 of the present volume. To both author and pubUshers the thanks of the 

 scientific world are due, and it is to be hoped that this interesting innova- 

 tion in publishing will meet with success. The quantum theory of spectra 

 is still being rapidly developed, and it is inevitable that before long this 

 report will be out of date. It will remain, however, as a guide to the early 

 development of the theory. We venture to express the hope that it will 

 be found possible, at some subsequent date, to bring out a second edition 

 in which further developments of the theory will be summarised. 



H. S. J. 



Petit Atlas Celeste. Par G. Bigourdan, Membre du Bureau des Longitudes. 

 [Pp. 54, with 5 star-maps in two colours.] (Paris : Gauthier-Villars 

 & Cie, 1920. Price 2 fr. net 4- 50 per cent.) 



This small volume contains five star-maps, covering the whole sky and 

 showing all stars down to and including the 5th magnitude, and a propor- 

 tion of those fainter than 5" but brighter than 5^5, where the inclusion of 

 these does not produce confusion. The two polar caps down to declivations 

 ± 50° are presented in two of the maps, whilst the equatorial zone between 

 declinations ± 50° is presented in three maps, each covering 8 hours of 

 right ascension. They thus contain the brighter naked-eye stars. Un- 

 fortunately the maps, which are reprinted from the Annuaire of the Bureau 

 des Longitudes, are anything but clear, and are on too small a scale to prove 

 of much value. The figures representing the names of the constellations 

 could have been omitted with some gain in clearness, and, apart from this, 

 they are by no means artistic. 



The maps are preceded by a brief but useful introduction, giving a list 

 of the constellations, with their Latin names and French equivalents, and 

 of those whose names are no longer in use ; the positions and brightness of 

 the brighter stars in each constellation ; and other matter. If better maps 

 were provided, the volume would prove a useful and compact reference- 

 book for beginners in the study of the heavens. H. S. J. 



The Sumner Line or Line of Position as an Aid to Navigation. By G. C. 



CoMSTOCK. [Pp. vi -f 70, with 6 figures and 2 charts.] (New 

 York : John Wiley & Sons. London : Chapman & Hall, 1919. 

 Price 6s. net.) 



Blank Reduction Forms for Line of Position Observations, Marcq St. Hilaire 

 Method, with Explanations of Use. By G. C. Comstock. (New 

 York : John Wiley & Sons. London : Chapman & Hall. Price 

 2s. 6d. net.) 



This small volume is intended to explain the Sumner line method of fixing 

 the position of a ship at sea to readers who already possess some knowledge 

 of navigation. The Sumner line method possesses such great advantages 

 over the older methods that it is surprising that it has not as yet com- 

 pletely displaced them. We believe, in fact, that its use is far from being 

 general. Any volume which will help further to popularise the method 

 is therefore to be welcomed. But we are doubtful whether the present 

 volume will serve this purpose, at any rate on this side of the Atlantic. 



The author has not, as might have been inferred from the title, dealt 

 with the general problem of the line of position, but only with the particular 

 method due to Marcq St. Hilaire. Inasmuch, however, as the St. Hilaire 

 method is the best and the one most generally adopted, this cannot be con- 

 sidered a disadvantage. The treatment is straightforward, but is not the 

 simplest that we have seen. Moreover, from the point of view of English 



