26 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
ment of the titles on hand includes only those of works published 
before January 1,1882. <A large amount of material for subsequent 
years has been collected but has not been submitted to classification. 
It may be included in supplementary volumes, or incorporated with 
the bibliography if publication be delayed. 
The chief sources of material and approximate number of titles 
added to the bibliography, after the rejection of duplicates, are as 
follows : 
Prof. Symons’ catalogue ; : ‘ : : . 18,000 
Royal Society catalogue, i-viii : : Z : j 11,000 
Hellmann, Repertorium . 5,000 
Printed catalogues and bibliographies, including R Reuss, Poggendorf ‘ 
&e. (400 vols.) ¢ : 4,000 
Manuscript catalogues and bibliographies . . : . 3,000 
Periodicals indexed (6,400 vols.) . , : : 3 12,000 
Total number before final revision . - - 53,000 
Number of independent titles after final revision, about 50,000 
The duplication of titles by double classification will increase the 
number of entries to about 55,000. 
The form adopted for the work is that of a classed subject cata- 
logue, with full author index. The general plan of the subject 
catalogue is similar to that of the Poulkova catalogue and that 
adopted by Drs. Houzeau and Lancaster for their Bibliographie 
générale de Pastronomie, the arrangement being chronological under 
each subject. The classification is based upon a scheme submitted 
by Dr. Lancaster, at the request of the Signal office, some minor 
modifications having been made after careful study and consulta- 
tion with other meteorologists and bibliographers. 
The general divisions of the classification are shown by the fol- 
lowing outlines : 
A. History and bibliography. 
LG  duekeorelos B. General and collected works. 
areas 8Y-1 ©. Organization and methods. 
D. Instruments. 
(1. Temperature. 
= : 
(A. Physics of the at- } 3. scat 
| Zouaphena. ls Optical phenomena. 
TL ‘theoratieat aes 5 ma is 
teorology. BO NWidahinnios. Or ake 2 Generali 
| atmosphere. Storess! 
L 
C. Cosmic relations of wis eee 
