After I warned the nurse taking blood that it would be very hard to find a vein on me, she said, "Don't worry. We've seen worse. Last year we had a girl come in to get a blood test for her marriage license and we had to stick her six times in four places before we got anything."
"Yes, I know," I said. "That was me!"
PhotophoneIn 1882, the photophone was demonstrated by Alexander Graham Bell and Charles Sumner Tainter. In their device, a mirrored silver disc was made to vibrate by speech from a speaking tube. Light reflected off the disc was focused by a parabolic dish onto a selenium photocell. The variations in the reflected light were converted into electrical signals carried to headphones. |
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