From 1800 to 1900, New York City changed from a small seaport village of 30,000 to an international city of 4 million, all living below 57th Street. The result? Human congestion, filth, rot and disease.

David Rosner, professor of history and co-director of the program in the History of Public Health and Medicine at Columbia's School of Public Health, paints a vivid portrait of a budding city in ecological crisis in this feature available at www.fathom.com beginning March 30.

Fathom.com, the Columbia-affiliated authenticated knowledge site, presents new features on a variety of topics on its homepage each week. The following features will premier this week on the Fathom homepage:

Mon., April 2: The Instantaneous Vision (American Film Institute), a video discussion among a group of filmmakers and industry experts on how video empowers filmmakers in both the production and post-production process, by Michael Rubin, Randal Kleiser, John Peterson, Jacques Thelemaque, Terry Ragan and Ronald Stein, participants in AFI's Digital Symposium.

Tues., April 3: Clemens and Vivanco: A Concert of Early Music (Columbia). Nine audio clips and accompanying text explore the influence of Franco-Flemish and Italian art on composers Clemens and Vivanco. George Steel, executive director of Columbia University's Miller Theater directs, the Vox Vocal Ensemble.

Wed., April 4: War and Democracy (London School of Economics). The most important aspect of globalization is the end of interstate war and the beginning of "new wars" or "spectacle wars" caused by transnationalist nationalist and fundamentalist groups and involving long-distance, high-technology air wars. Text by Mary Kaldor, director of the Programme on Global Civil Society at the Center for the Study of Global Governance at the London School of Economics and Political Science.

Fathom offers e-courses and for-fee seminars as well as free features and includes over 60,000 authenticated references, from the world's leaders in education, research, and the dissemination of knowledge.