Lesson 115


Jeans are pants. They’re normally made of denim or dungaree. Denim is cotton that’s really thick and strong. It’s blue because of the indigo dye. A lot of natural dyes penetrate cloth, but indigo dye only gets the surface. When you wash the dyed jeans, a little of the dye is removed and it pulls some threads with it. It then softens the jeans. Levi Strauss made the cloth, but Jacob Davis got the idea. They became partners in business and when Davis patented it, the men made a deal that allowed Strauss to have manufacturing rights. Since Davis riveted it, it was stronger. Miners and cowboys used jeans. This was my favorite invention.


A fire sprinkler is a sprinkler that goes off in a fire. It protects property and buildings. And it can protect lives. Henry Parmalee invented the fire sprinkler to protect his pianos in his piano shop. He didn’t have insurance, so he invented it to protect his pianos. Holding as a plug was an element that melted easily, so when the heat from fire melted it, it would spray water.
People now have sprinklers. A man named Grinnel patented a more improved, better version.


The QWERTY keyboard is one of the most popular keyboards. It allows you to type quickly and not get easily tired. Christopher Sholes invented the QWERTY keyboard. When old typewriters were invented, the keys often jammed and so Sholes tried to fix that. He created it so the work of both hands is contributed. People tried to make Sholes’ QWERTY, but slightly different and were unsuccessful. The QWERTY keyboard was my favorite invention.


A dentist drill is made for drilling out cavities, because if they aren’t drilled out, it can cause even more decay and ruin your teeth. Ancient dentists knew about cavities, and how they needed to be drilled out. The hand drills were slow and painful, though. Some people made faster and improved versions. But George Green’s drill used electricity, and it was extremely fast. Dentists can now drill out cavities. It’s a called a “handpiece” sometimes because “dentist drill” sounds terrifying.


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