In 1904, a terrible fire raged in Baltimore. Firefighters arrived on special trains from Washington, D.C., and other places as far away as New York City. But most of the crews were helpless to put out the fire since their hoses would not fit on Baltimore hydrants. More than 1,500 buildings covering more than 70 city blocks burned to the ground. NIST found there were more than 600 different fire hose sizes and hydrant connectors in use in the U.S. In 1905, NIST helped pick a national fire hose standard that was eventually adopted throughout the country.

One morning in 1918, President Wilson, an avid reader of mystery novels, sent an envelope bearing a wax Presidential seal to NIST. Wilson had read that a letter with such a seal could be read and resealed without any sign of tampering. He asked NIST in his sealed letter if it were true. The next day he had his letter back, apparently still sealed. Inside were the lead disks NIST made overnight to produce the fake seal.

In the 1920s, purple, orange, green, blue, yellow, and red traffic lights carried different meanings in different states. In some states, green meant “go” and in others it meant “stop.” In 1927, NIST worked with two other agencies to establish a national code for the color of traffic lights that we still use today.

Instructions for a 16th-century measuring rod:
“Take 16 men, short and tall ones as they leave church and let each of them put one shoe after the other and the length thus obtained shall be a just and common measuring rod to survey the land with.”

Created: May 8, 2001
Last updated: August 15, 2001
Contact: inquiries@nist.gov