TRANSACTIONS OF SKCTION A. 593 



lie closer together over all tlie elevated points — as, for example, niovutains, cliurc-h 

 .towers, &c. On the basis of these facts I think it easy to explain the electricity of 

 thunderstorm clouds. In fact every cloud, or every part of a cloud, may he con- 

 sidered as a leading conductor, especially such clouds as have for the most part 

 perpendicular height. After being induced the charge results by supposing a ' con- 

 vection ' of electricity either from the upper or from the lower side, according to 

 greater or smaller speed of the air in the height. In the first case, the clouds 

 will be charged with positive electricity ; in the other, with negative electricity. 



I am inclined, therefore, to state that the electricity of thunderstorm clouds 

 must be considered as a special but disturbed case of the normal electric state of the 

 atmosphere, and that all attempts to explain the thunderstorm electricity must he 

 based on the study of the normal electricity of the atmosphere. 



3. The General Bibliography of Meteorology and Terrestrial Magnetism. 

 Compiled ly the Signal Office at Washington. By Cleveland Abbe. 



The rapid increase of the literature of the sciences makes a complete index to 

 the published memoirs for each special department a matter of the greatest 

 importance to the student, and equally so to the practical man. The astronomical 

 bibliographies of Struve and Houzeau and Lancaster, and the great Index-catalogue 

 of the library of the Surgeon-General's Office, by Billings, are examples of the high 

 esteem in which special bibliographies are held ; and if the Signal Office does not 

 ■emulate the exhaustive character of these monumental labours, it lias at least 

 attempted to compile an index to the literature of meteorology that shall have 

 practical value and realise a desideratum that has long been felt by the younger 

 students of the science of meteorology. 



The urgent need of an index to the literature of meteorology was expressed at 

 the general congresses of meteorologists at Vienna and Rome, and a special com- 

 mittee on this subject was appointed by the International Meteorological Committee 

 in 1880. Mr. Hellmann and Mr. Scott composed this committee, and the principal 

 results of their deliberations were, first, the discovery of the fact that much work had 

 already been accomplished by private effort, and, second, a great stimulus given 

 to the whole subject, based on the evident possibiHty of making a successful com- 

 bined efibrt. The final conclusion of the committee was to the effect that, for the 

 present, it was best to secure from each country the publication of a bibliography of 

 its own literature in the department of meteorology. 



While the committee were still considering the subject. General W. B. Hazen, 

 ■who had succeeded General Myer as the chief signal officer, decided that the daily 

 needs of the weather bureau at Washington justified the compilation of a general 

 bibliography covering all the subjects in which that office was interested. With 

 the permission of the Secretary of War he therefore obtained a copy of the card 

 catalogue compiled by Mr. Symons of London, on which copy that gentleman kindly 

 spent great labour towards its perfection, and of the card catalogue that I had. 

 compiled by selection of titles from the great index of the Royal Society. With 

 this as a nucleus, General Hazen authorised letters to be sent inviting the co-opera- 

 tion of all weather bureaux, observatories, and authors, in the preparation of a com- 

 plete general bibliography. The responses to these requests have been most 

 gi'atifying, and with these manuscript collections have been incorporated all acces- 

 sible printed lists of titles. The more important series of periodicals have been 

 examined anew, and special searches have been made in the libraries of Europe 

 and America for pamphlets and rare publications. 



The resulting index now contains over fifty thousand titles of works, written 

 by over twelve thousand authors. The cards are arranged by subjects with full 

 author inde.x ; the classification by subjects includes over one hundred and sixty 

 subdivisions, covering general meteoi'ology, climatology, dynamic meteorology, the 

 theory of instruments, history and bibliography, special storm studies, weather 

 prediction, observations, and a rather full list of subjects intimately connected with 

 meteorology proper, such as the relations of the atmosphere to animal and vege- 

 table life, disease, &c. 



1887. Q Q 



