Sun smarts
Article Abstract:
The sun protection factor (SPF) of a sunscreen indicates how long it will provide protection in the sun, but the figure is not precise. An SPF of 30 provides only slightly more protection than an SPF of 15. Layering different SPFs does not provide additional protection.
Publication Name: Parenting
Subject: Family and marriage
ISSN: 0890-247X
Year: 1996
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First fired, first forgotten
Article Abstract:
The first motorcycle which was steam-powered was invented by Sylvester H. Roper between 1868 and 1869. Roper was also responsible for building eight steam-powered cars. He died of a heart attack at the age of 73 after he was thrown off his motorcycle.
Publication Name: Cycle World
Subject: Sports and fitness
ISSN: 0011-4286
Year: 1998
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The leaning tower of Pisa
Article Abstract:
Architects, engineers and historians are using new technology to save the 800-year old leaning tower of Pisa. The tower is 5.227 meters off-center and continues to tilt at 1.2 millimeters each year.
Publication Name: Scientific American
Subject: Science and technology
ISSN: 0036-8733
Year: 1995
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