History 4 lesson 155

Lightning Rod 

The Leyden (leiden) jar was invented in 1744, news spread across the ocean and reached Ben Franklin. Franklin became very interested in electricity by 1746. He noticed static electricity sparks looked like lighting. From this he devised his famous kite experiment. Lighting rods are metal spikes placed on tall buildings. Lighting can develop a billion volts and 300,000 amps. Electric fields become so strong they break down the insulating property of air. Lightning rods work as part of a lighting protection system. Used to protect all kinds of structures. Franklin installed them on public buildings in 1752. Lightning wasn’t well understood though to be evil spirits. They became controversial in the pulpit: thwarting God’s vengeance. In France a court case erupted over a man who installed a lighting rod.

Benjamin Franklin

Franklin was born in Boston in 1706. He wanted to be a sailor but his father wanted him to be a preacher. He became an apprentice instead. Franklin was always a learner; he founded a successful newspaper and became a freemason. Franklin was one of America’s first inventors. His “Franklin Stove” improved heat production efficiency,  and he invented bifocals. His autobiography was one of the most successful of its kind. Franklin became a founding Father, his newspaper increased his fame. So did his inventions. Poor Richard’s Almanck was most influential. It contained proverbs which are still recited today. As an ambassador, he was a model statesman. 

Glass Harmonica

Glasses partially with water can “sing”. Irishman Richard Pockrich popularised the “instrument” in the 1700s. Englishman Edward Deleval refined the instrument. He caught Benjamin Franklin’s attention. Franklin invented the glass harmonica as a variation of the original glass harp. Franklin’s instrument produced a sweet sound. It sat on it’s side and spun using a foot pedal.The instrument sounds “Ethereal” because of how we interpret sound. It wasn’t loud enough to fill an entire hall with sound. The instrument became popular for a while. Thousands had been sold by the time Franklin died (1790). Strange things happened which sent its popularity into decline. Franz Mesmer was a German who developed an idea of “animal Magnetism”. 

Swivel Chair

Thomas Jefferson was born in Virginia in 1743.  He got a great education and became a lawyer He took a scientific interest in agriculture and architecture. Heffrson invented lots of small practical devices. Including the swivel chair. Swivel chairs rotate on an axis in circles. Jefferson modified a vulgar sitting chair, Swivel chairs have maneuverability. Wheeled chairs provide convenience. Everybody likes swivel chairs. Franklin didn’t want to write the declaration because he didn’t want his words changed. Jefferson wrote it in his swivel chair. Scientific management focused on work efficiency.            

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