History 5 Lesson 65


Mining was important but hazardous. Early jackhammers were inspired by steam engines, developed by 1806. Jonathan couch invented the modern jackhammer in 1848. Jackhammers are “hammer drills”. The bit is pushed up and down pressurized air. The modern jackhammer can run on electricity. Steam engines couldn’t be installed inside mines. They produce hazardous gases. Couch’s assistant, Foul innovate the jackhammer to use compressed air. It could also be used to ventilate the mines. Demonstrations were performed to investors. 

Pin-Tumbler Lock

Linus Yale Sr. was born in Connecticut in 1797. He opened a lock shop in his 46’s. Yale invented pin-tumbler lock in 1843. Lock contains pins in a cylindrical drum. The key lines up pins to rotate the cylinder. Each pin has two parts. These locks are harder to pick than the old locks. They are easy to re-key. Linus Yale Jr. continued his father’s work. Became a mechanical engineer. His locks received widespread acclaim. He demonstrated them at the World’s Fair. Advertised 9 important benefits Yale exposed vulnerabilities in competitor’s locks.

Safety Pin

Walter Hunt was born in New York in 1796. Hunt invented a version of the sewing machine in 1832. He had experience with needles and the sewing industry. He invented the safety pin in 1849. Safety pins are simple folding needles. Pins have sharp heads that can stick you. The safety pin guards the head within a clasp. They fasten fabric and other materials together. Hunt made 27 times his debt level when he sold the patent. They were simple to manufacture. They were advertised to nurses and housewives for diapers and clothes. They were acquired by a large chemical company.


Leon Foucult was born in Paris in 1819. He became interested in Physics. He helped discover the speed of light. He did an experiment to prove rotation of earth in 1851. He invented the gyroscope in 1852. Gyroscope: spinning disc set inside gimbals. It seemed to defy laws of physics (they don’t). The gimbals allow rotation. They resist forces that try to turn them. Gyroscopes create stability. Foucult used gyroscopes to prove earth’s rotation. Electric motors applied in the 1860s. Gyroscopic compass built in 1904.          

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