Welcome to Fourmilab North America

Last update: 3 July 2018

This site is developed and maintained by John Walker, founder of Autodesk, Inc. and co-author of AutoCAD. A variety of documents, images, software for various machines, and interactive Web resources are available here; click on entries in the frame to the left to display a table of contents for that topic. Items which span more than one category are listed in all.

A comprehensive (and large) list of all items on the site is available as a frame- and graphics-free Site Map.

Except for a few clearly-marked exceptions, all the material on this site is in the public domain and may be used in any manner without permission, restriction, attribution, or compensation. Back links to this site are welcome.

Fourmilog: Site Update and Web Log
John Walker's Reading List
Fourmilab Photo Album
Follow Fourmilab on Twitter

New and frequently-visited pages

New: Simulated Annealing: The Travelling Salesman Problem
New: Nixie Tube Clock
New: Cosmic Rays on a Plane!, Hot Stuff in the Kitchen, and A Radioactive Lens
New: Talkin 'Bout My Innovation
New: Univac Document Archive
New: Fifty Years of Programming and Moore's Law
New: Commodore Curiosities
New: Marinchip Systems: Documents and Images
New: ISBNiser: Validate, interconvert ISBN-10 and ISBN-13, generate Amazon links
New: Apparent Diurnal Variation in Background Radiation
 
JavaScrypt: Browser-Based Cryptography
The Digital Imprimatur and The Internet Slum
HotBits: Random numbers from radioactive decay
The Autodesk File
Earth and Moon Viewer
The Hacker's Diet
Paleo Postings The paleo diet and lifestyle
Solar System Live
Your Sky
Total Solar Eclipse 2010, 2008, 2001, and 1999
Bipolar: North Pole (2008), South Pole (2013)
The Analytical Engine