When Were Contact Lenses Invented?
When Were Contact Lenses Invented? Some say German glassblower F.A. Muller used Herschel’s ideas to create the first known glass contact lens in 1887. Other...
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Where Is the Aorta?
Where Is the Aorta? The aorta is the great artery rising from the left side of the heart, through which the blood passes on its way to all parts of the body except the...
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What Is a Tattoo?
A tattoo is a marking made by inserting indelible ink into the layer of skin to change the pigment for decorative or other reasons. Tattoos on humans are a type of...
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Why Do Butterflies and Moths Have Powdery Wings?
Why Do Butterflies and Moths Have Powdery Wings? The “powder” on the wings of moths and butterflies is really a layer of tiny, colored scales which overlap...
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What Causes Whirlwinds?
What Causes Whirlwinds? Whirlwinds are caused by the rising of an overheated layer of air close to the ground. Whirlwinds occur when the sun heats the air near the...
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