http://www.tornadoproject.com/myths/myths.htm
For nearly a century, the published conventional wisdom was that the southwest corner of a building, both above and below ground, afforded the best protection. This misconception probably originated from someone's reasoning, rather than from actual observations. They probably assumed that deadly debris would be propelled over the southwest corner and land in the northeast corner.
The idea that it was safe to seek shelter on the side of a house facing the oncoming tornado dates back to at least the first book on tornadoes, the 1887 comprehensive text Tornadoes, by John Park Finley. He placed in italic for emphasis the following remark: "Under no circumstances, whether in a building or in a cellar, ever take a position in a northeast room, in a northeast corner, or an east room, or against an east wall." He also recommended removing the furniture from the west-facing room and closing all windows in the house. This is all incorrect, deadly, and time-wasting advice. It is quite possible that someone has died following it. While relatively few people probably read the book when it was available, the advice was quoted in many newspapers. It is possible that in the limited number of damage surveys that Finley conducted personally, he came upon a grisly scene involving the northeast portion of a poorly constructed house that had fallen over, and it strongly influenced his thinking.
These assumptions went essentially unchallenged until 1966, when Professor Joseph Eagleman of the University of Kansas undertook a survey of destroyed produced by after the Topeka tornado of June 8th. Professor Eagleman's objective study showed that the south side and southwest corners, the direction of approach for the Topeka tornado, were the least safe areas, and the north side of homes were the safest .... both on the first floor and in the basement. He repeated the study after the Lubbock, Texas tornado of May 11, 1970, and the results were even more striking. The southwest portion of the houses were unsafe in 75% of the damaged homes .... double the percentage of unsafe areas in the northeast part of homes. As a general rule, people in basements will escape injury despite the extreme devastation above them. Being under a stairwell, heavy table, or work bench will afford even more protection.
Ignorance of this conventional wisdom, combined with common sense, has saved lives in the past. At the Pacolet Mills near Gainesville, Georgia on June 1, 1903, 550 people ran to the northeast corner of the building as the tornado approached from the southwest. That northeast corner was the only part of the building not destroyed. At least fifty people died in other Gainesville fabric mills on that day, and more than 40 more died in homes near the mills.