Too much care cannot be taken to distinguish between books written by different authors, but bearing the same name. Many catalogues are full of errors in this respect, attributing, for example, works written by Jonathan Edwards, the younger, (1745-1801) to Jonathan Edwards the elder, (1703-58); or cataloguing under Henry James, Jr., the works of his father, Henry James. The abundant means of identification which exist should cause such errors to be avoided; and when the true authorship is fixed, every author's chronology should appear next after his name on every card-title: e. g. James (Henry, 1811-82) Moralism and Christianity, New York, 1850. James (Henry, 1843- ) Daisy Miller, N. Y. 1879.

The designation of book sizes is a vexed question in catalogues. The generally used descriptions of size, from folio down to 48mo. signify no accurate measurement whatever, the same book being described by different catalogues as 12mo. 8vo, crown 8vo. &c., according to fancy; while the same cataloguer who describes a volume as octavo to-day, is very likely to call it a duodecimo to-morrow. Library catalogues are full of these heterogeneous descriptions, and the size-notation is the bête noir of the veteran bibliographer, and the despair of the infant librarian. Yet it is probable that the question has excited a discussion out of all proportion to its importance. Of what consequence is the size of a book to any one, except to the searcher who has to find it on the shelves? While the matter has been much exaggerated, some concert or uniformity in describing the sizes of books is highly desirable.

A Committee of the American Library Association agreed to a size-notation, figured below, adopting the metric system as the standard, to which we add the approximate equivalents in inches.

Sizes.  Size abbreviations.  Centimetres
outside height.		  Inches.
Folio, F°.F4016
Quarto, 4°.Q3012
Octavo, 8°.O2510
Duodecimo, 12°.D208
Sixteen mo., 16°.S17.57
Twenty-four mo., 24°.T156
Thirty-two mo., 32°.Tt12.35
Forty-eight mo., 48°.Fe104

It will be understood that the figure against each size indicated represents the maximum measure: e. g. a volume is octavo when above 20 and below 25 centimetres (8 to 10 inches high).

As this question of sizes concerns publishers and booksellers, as well as librarians, and the metric system, though established in continental Europe, is in little use in the United States and England, it remains doubtful if any general adherence to this system of notation can be reached—or, indeed, to any other. The Publishers' Weekly (N. Y.) the organ of the book trade, has adopted it for the titles of new books actually in hand, but follows the publishers' descriptions of sizes as to others. Librarian J. Winter Jones, of the British Museum, recommended classing all books above twelve inches in height as folios, those between ten and twelve inches as quartos, those from seven to ten inches as octavos, and all measuring seven inches or under as 12mos. Mr. H. B. Wheatley, in his work, "How to Catalogue a Library," 1889, proposed to call all books small octavos which measure below the ordinary octavo size. As all sizes "run into each other," and the former classification by the fold of the sheets is quite obsolete, people appear to be left to their own devices in describing the sizes of books. While the metric notation would be exact, if the size of every book were expressed in centimetres, the size-notation in the table given is wholly wanting in precision, and has no more claim to be adopted than any other arbitrary plan. Still, it will serve ordinary wants, and the fact that we cannot reach an exact standard is no reason for refusing to be as nearly exact as we can.

And while we are upon the subject of notation may be added a brief explanation of the method adopted in earlier ages, (and especially the years reckoned from the Christian era) to express numbers by Roman numerals. The one simple principle was, that each letter placed after a figure of greater equal value adds to it just the value which itself has; and, on the other hand, a letter of less value placed before (or on the left of) a larger figure, diminishes the value of that figure in the same proportion. For example:

These letters—VI represent six; which is the same as saying V+I. On the contrary, these same letters reversed represent four; thus—IV: that is V-I=4. Nine is represented by IX, i. e., X-I, ten minus one. On the same principle, LX represents 60—or L+N: whereas XL means 40—being L-X. Proceeding on the same basis, we find that LXX=L+XX=70; and LXXX or L+XXX is 80. But when we come to ninety, instead of adding four X's to the L, they took a shorter method, and expressed it in two figures instead of five, thus, XC, i. e. 100 or C-X=90.

The remarkable thing about this Roman notation is that only six letters sufficed to express all numbers up to one thousand, and even beyond, by skilful and simple combinations: namely the I, the V, the X, the L, the C, and the M, and by adding or subtracting some of these letters, when placed before or after another letter, they had a whole succession of numbers done to their hand—thus:

I,1XX,20CC,200
II,2XXX,30CCC,300
III,3XL,40CCCC,400
IV,4L,50D,500
V,5LX,60DC,600
VI,6LXX,70DCC,700
VII,7LXXX,80DCCC,800
VIII,8XC,90CM,900
IX,9 C (centum),100 M, (mille),1,000
X,10