s of December 10, 1998), maps
(171,756), serials (825,664), prints and photographs (68,135), manuscripts
(10,698), music (209,142), visual materials (278,771) and software (6,318). As
explained on the website:

"The Experimental Search System (ESS) is one of the Library of Congress' first
efforts to make selected cataloging and digital library resources available over
the World Wide Web by means of a single, point-and-click interface. The
interface consists of several search query pages (Basic, Advanced, Number, and a
Browse screen) and several search results pages (an item list of brief displays
and an item full display), together with brief help files which link directly
from significant words on those pages. By exploiting the powerful synergies of
hyperlinking and a relevancy-ranked search engine (InQuery from Sovereign Hill
Software), we hope the ESS will provide a new and more intuitive way of
searching the traditional OPAC (on-line public access catalog). [...]

Besides the cataloging records for over 4 million books (including JACKPHY
records not currently available through SCORPIO); 263,000 motion pictures,
videos, filmstrips and other visual work; 200,000 sound recordings and musical
scores; more than 150,000 maps; and 4,300 computer files - i.e., LC cataloging
records created since 1968 - ESS also contains the cataloging for almost 140,000
photographs and manuscripts in the National Digital Library Program's American
Memory, linking to more than 70,000 digital photographs and images available
on-line. By indexing the works selected and organized by The On-Line Books Page
at Carnegie Mellon University, links are also provided to the full-text of over
2,500 on-line books from sites across the Internet. Even early motion pictures
are available for searching and viewing once the proper viewer is installed.
(Hint: try searching on the subject heading 'shorts' in the Photographs,
Manuscripts, Movies collection.)"

Except for their prohibitive costs, the commercial databases give us an idea of
what the catalogs could be in the future: for the past several years the Dialog
Corporation, Lexis-Nexis or UnCover have been using their catalogs to provide
on-line documents.

Based in London, United Kingdom, with regional headquarters in Mountain View,
California, and Hong Kong, the Dialog Corporation is a major on-line information
company, with 900 main databases (the most well-known being Dialog and Profound)
serving over