114 



SCIENCE. 



[Vol. I., No. 4. 



the accompanj'ing figure of the curve of fre- 

 quencj' of astronomical publications. Notice 

 in the curve the dates of the discovery of Nep- 

 tune (1846), of the transit of Venus (1874), 

 of the French Revolution (1794) , of the wars of 

 Napoleon (1815), etc. 



The number of authors per centur}' is : — 



1601-1700 88 



1701-1800 571 



1801-1880 2,901 



The number of articles per centurj^ is : — 



1601-1700 396 



1701-1800 3,479 



1801-1880 18,970 



The proportion of articles per author is : — 

 1600-1699 .... 4.5 articles per author. 

 1700-1799 .... 6.1 " " " 

 1800-1880 .... 6.6 " " " 



The following list of authors who have fur- 

 nished more than a hundred articles convej's 

 its own lessons : — 



Articles. Per year. 



1. Secchi . . . 360, 1846-1878 . . . 10.9 



2. Lalande. . . 299, 1743-1807 ... 4.6 



3. Zach, F. X. de . 252, 1785-1832 ... 5.3 



4. Bessel . . . 243, 1805-1846 ... 5.8 



5. Flaramarion , 210, 1863-1881 . . . 11.1 



6. Bii-t .... 207, 1857-1881 ... 8.3 



7. Proctor . . . 178, 1865-1881 . . . 10.5 



8. Gruithuisen . 177, 1817-1850 ... 5.2 



9. Faye .... 177, 1846-1881 ... 4.9 



10. Madler . . . 169, 1831-1870 ... 4.2 



11. Le Verrier . . 164, 1839-1877 ... 4.2 



12. Cassini, J. D. . 143, 1664-1709 ... 3.1 



13. Wolf, R. . . 142, 1844-1881 ... 3.7 



14. Laplace . . . 135, 1772-1827 ... 2.4 



15. Airy .... 134, 1826-1881 ... 2.4 



16. Bode .... 124, 1775-1826 ... 2.4 



17. Lockyer. . . 120, 1864-1881 ... 6.7 



18. Encke . . . 117, 1819-1865 ... 2.5 



19. Arago . ... 110, 1814-1853 ... 2.8 



20. Delambre .« . 107, 1783-1822 ... 2.7 



21. Heis .... 106, 1847-1877 . . . 3.4 



22. Euler, L, . . 105, 173.5-1783 ... 2.1 



23. Hansen . . . 105, 1824^1874 ... 2.1 



It will be evident that this book is indispen- 

 sable to everjr astronomical librarj- ; and the 

 smaller the librarj', the more important such a 

 work becomes. Much of the material of this 

 work has been incorporated in another work 

 hj M. Houzeau : Vade-mecum de I'astronome, 

 Brus.sels, 1882 ; 28-f-l,144 p. 8vo. 



For each of these works, astronomy and 

 ever}' astronomer owes a debt of gratitude. 



EDVSfARD S. HOLDEN. 



THE FORMATION OF COAL. 



Mdmoire sur la formation de la liouille ; par Grand'- 

 Eury. V&ni, Dunod. 1882. 196 p., 4 pi. 8°. 



This work of Grand'pjury, reprinted from 

 the Annales des mines for 1882, exposes upon 



the origin of the coal such an array of facts, 

 considerations, hypothetical subjects of in- 

 quiries, and assertions based upon long and 

 careful researches, and these are scattered 

 in so many chapters, that the only possible 

 way to give an idea of the scope of the work 

 is to quote the titles of the essential divis- 

 ions. 



The first part considers the botany and 

 stratigraphy of the carboniferous formations, in 

 seven chapters : 1°. State of disintegration of 

 the plants ; 2°. Distribution of the remains 

 of fossil plants in the rocks ; 3°. Structure of 

 coal, and its organic composition ; 4°. Trunks 

 and stipes in situ; fossil forests and carbonif- 

 erous forests, their relation to coal-beds ; to- 

 pographical circumstances ; 5°. Examination 

 of the fossil stems and of the lignite, and 

 their comparison with coal-beds ; 6°. Peat- 

 bogs and other deposits of vegetable matters ; 

 7°. Critical revievr of the divers theories on 

 the formation qf coal. 



The second part treats of the phj'sical and 

 chemical characters as follows : 1°. State of 

 the vegetable remains in coal ; 2°. Physical 

 properties of coal ; 3°. Chemical composition ; 

 4°. Comparison of the characters of fossil 

 wood, lignite, and peat ; 5°. Circumstances 

 which have fostered the transformation of 

 coal; 6°. Conclusions and resume. 



Each of the above chapters is subdivided 

 into a number of sections, ninetj- in all, each 

 with a title, and a short exposition of the 

 contents. From his long researches in the coal- 

 fields of Europe, the author comes to the con- 

 clusion that the matter composing the coal is 

 of vegetable origin, derived from plants grown 

 in situ, rapidlj' decomposed under atmospheric 

 influence, more slowly transformed bj' macera- 

 tion, and later washed out bj' torrential floods 

 of rain, transported and deposited in depres- 

 sions or basins surrounded bj^ swampj' forests, 

 — the coal, in his opinion, being the result of 

 stratification like the rocks. Besides the many 

 other objections which could be made against 

 this theory (a theorj^ suggested to the author 

 bj' the small areal surface occupied by the coal- 

 deposits of France) we may mention the wide 

 extent of the American coal-fields, and the 

 continuity' of some of the beds which cover 

 areas of many hundred square miles, as suf- 

 ficient to contradict the assertions of the dis- 

 tinguished author. Nevertheless, the book 

 is very instructive as exposing a niass of 

 facts concerning the divers phases of a for- 

 mation, which, though often considered by 

 science, are still, some of them at least, unex- 

 plained. 



