A list of the "Works indexed, nearly fourteen hundred in number, arranged alpha- 

 betically according to the contractions employed in the Catalogue, will be found 

 at the end of this Introduction ; and in it those volumes which could not be pro- 

 cured, and the absence of which breaks the continuity of a series, have been carefully 

 marked as deficient. The Royal Society hope that the publication of these deficien- 

 cies may lead to copies of the Titles contained in the missing volumes being 

 forwarded to them for insertion as the Catalogue proceeds. 



When possible, both the Volume and the Year have been given, one reference 

 acting as a check upon the other ; and this avoids the necessity of marking the 

 various Series. In the case of Transactions of Societies, Ephemerides, and Astro- 

 nomical Almanacs, the year to which the volume belongs, and not the year of publi- 

 cation, has been given. Thus the Nautical Almanac for 1863 was published in 

 1860, but the former year is adopted in the Catalogue as that by which this 

 particular volume is known. 



A date enclosed in brackets marks the time when a paper was read, which 

 occasionally precedes by some years the date of the volume in which it is printed. 



b. Period of Time embraced. 



The Catalogue is intended to comprise Transactions and Journals published in the 

 period between 1800 and 1863 inclusive. 



A few important series, beginning towards the end of the last century, which it 

 seemed undesirable to break, are indexed from their commencement. The point 

 at which any serial work was taken up may at once be seen by turning to the list at 

 p. xiii. It has also been necessary to exceed the limit in the other direction, so as 

 to include Memoirs which were read in 1863, though not printed until a year or 

 more after. 



c. General Arrangement of the Catalogue. 



The Titles are arranged alphabetically according to Authors' names, the arrange- 

 ment under the head of any one Author being chronological. Memoirs, which are 

 the work of two or more Authors, are entered under the name of each ; Reports 

 of Committees under the name of the Reporter. 



