"The Index givs similar or sinonimus words, and the same words in different connections, any any intelijent person wil surely get the ryt number. A reader wishing to know sumthing of the tarif looks under T, and, at a glance, finds 337 as its number. This gyds him to shelvs, to all books and pamflets, to shelf catalog, to clast subject catalog on cards, to clast record of loans, and, in short, in simple numeric order, thruout the whole library to anything bearing on his subject." (Dewey, Edition 11, p. 10) (Yes, that is how he spelled things.)The most recent version of DDC that I own is from 1922, so this example is an entry in the Relativ Index of Edition 11 under "Leaves:"
Leaves fertilizers 631.872
shapes of botany 581.4
In the schedules these classes are listed as:
631.872 : "Vegetable manures, Leaves" (coming right after "Vegetable manures, Muck").
581.4 : "Morfology comparativ anatomy"
You can see that the index is not just a repeat of the names of the points in the classification but is a kind of subject thesaurus on its own. It doesn't just point to the classification number but it gives some context ("fertilizers" "botany") to help the user decide which class number to select.
What I find odd today in libraries (mainly public libraries) is that we do not have an entry vocabulary for the Dewey classification. Libraries in the U.S. use the Library of Congress Subject Headings even when their classification scheme is Dewey. While LC subject headings will lead you to a catalog entry that has a classification number, they aren't an index to that classification scheme.
There are more oddities, actually.
One oddity is that we never explain these classification numbers to the users. Yes, I can go from the catalog to the shelf and find books that are near the one I am seeking, but in a small public library I can encounter a number of different topics on a single shelf; and in a large academic library I can wander whole aisles without seeing a change in the initial class number and have no idea if I have exhausted my topic area on the shelf as decimal points three places out change. Yet there is nothing either at the shelf nor anywhere else in the library to tell me what those numbers mean except usually at a very macro level. What I have before me are book spines and class numbers, and since I don't know what the class numbers mean I have to rely on the spine titles. So if I browse a shelf and see:
364.106 D26f The first family
364.106 En36h Havana nocturne
364.106 En36i The Westies
364.106 En36p Paddy whacked
... it may not be clear to me what topic I am looking at. At the very least I would like to be able to type "364.106" into an app on my phone and get a display something like:
300 Social sciences
360 Social problems & social services
(That example is truncated because the divisions to the right of the decimal point are not available to me. Presumably the display would take me down to .106, which would then have something to do with gangs and/or organized crime and/or mafia, but I'm just guessing at that.)
Even better, I'd like to point my phone camera at a book spine and get a similar read-out. Yes, I know that's not going to be simple.
Another oddity is that we put multiple subject headings on a bibliographic record, but only one classification number, reducing the role of classification to simply the ordering of books on the shelves. This means that there are subject headings on the records that would logically lead to class numbers other than the one that has been given.
Using my crime books as an example, the subject headings are clearly more diverse than the single classification code:
Mafia -- United States -- History
Mafia -- United States -- Biography
Criminals -- United States -- Biography
Organized crime -- United States -- Case studies
Lansky, Meyer, 1902-
Luciano, Lucky, 1897-1962
Mafia -- Cuba -- Havana
Cuba -- History -- 1933-1959
Havana (Cuba) -- Social conditions -- 20th century
Westies (Gang) -- History
Gangs -- New York (State) -- New York -- History
Irish American criminals -- New York (State) -- New York -- History
Hell's Kitchen (New York, N.Y.)
Organized crime -- United States -- History
Irish American criminals -- United States -- History
Gangsters -- United States -- History
This won't be a surprise to my readers, but this dual system is full of "gotchas" for users. If I look up "Irish American criminals" in the subject headings I retrieve some items in 364.106, some in the 920 area (biographies, but many users won't know that), and some in fiction (under the author's last name). It's not that there isn't a rhyme or reason, but there is nothing to explain the differences between these items to the library user that would justify going to three entirely different places in the library to explore this topic. My guess is that the system seems quite arbitrary.
Things are a bit better in libraries that use Library of Congress Classification (LCC) along with LCSH, since the two seem to be developed with some coordination. In his essay "The Peloponneasian War and the Future of Reference" Thomas Mann, of the Library of Congress, explains how LCSH and LCC work together:
"In order to find which areas of the bookstacks to browse, however, researchers need the subject headings in the library catalog to serve as the index to the class scheme. But the linkage between a subject heading and a classification number is usually dependent on the precoordination of multiple facets within the same string. For example, notice the specific linkages of the following precoordinated strings:This is the correlation that will appear in the LCSH documentation, but this is not what the user sees in the catalog. A search in LC's catalog for Greece-History-19th century brings up books with a variety of classification numbers, the first four being:
Greece–History–Peloponnesian War, 431-404 B.C.: DF229-DF230
Greece–History–19th century: DF803
Greece–History–Acarnanian Revolt, 1836: DF823.6
Greece–History–Civil War, 1944-1949: DF849.5"
DF803 .H45Again, the user is directed to different shelf locations from what seems to be a single subject heading, with no explanation of what these different locations mean.* It's got to be terribly confusing.
Compact notation is essential for the ordering of books on the shelf. But it seems truly odd that we order the books on the shelf but do not tell users what the order means. This can be seen as providing a delightful serendipity, but I presume that we could provide serendipity with less intellectual effort than has been dedicated to DDC and LCC, which are both enormously detailed and growing more so each year in an attempt to encompass the complexity of the published world. How much richer would the user's library experience be if she understood the relationship between the items on the shelf? Does it make sense to create detailed and complex relationships that then are not understood or used? What would a shelf system look like that was meaningful to library users? in a small library? in a large library? And, finally, can we use computing power to overcome to limitations that brought us to the situation we are in today in terms of organized subject access?
* Before someone explains to me that the first subject heading determines the class number... you know that, I know that, but millions of library users have no idea what the order of the subject headings means. Besides, library catalog users often don't see the full record with all of the subject headings. Even in the LC catalog subject headings are not included in the default display. We can't blame the users if they don't know what we don't help them know.