What is a normal dating timeline

Radar [1904, Christian Hülsmeyer by James Dyson] During the war, my mother worked for Bomber Command, shunting those little flags representing planes around the map of Europe.

She could plot things hundreds of miles away thanks to radio detection and ranging, now known as radar.

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Electrocardiogram [1903, Willem Einthoven] It had been known since the 17th century that muscular tissue would conduct electricity, and by the late 19th century, physiologists had investigated the possibility that the human body and heart, too, had electrical potential.

Then, in 1895, a brilliant young Dutch physiologist, Willem Einthoven, used a crude electrical sensing apparatus to establish that the beating heart produced four distinct signals, each one corresponding to a different ventricle.

Warm air in the room heated the ammonia which evaporated, absorbing heat and cooling the air until it reached its dew point.

The droplets that formed on the coils drained away and a fan returned the cooler, drier air to the printing plant.

I was stunned to discover that the walls of the bag were clogged with dust.

The airflow was being choked by the bag walls, causing a dramatic loss of suction.

He came up with a machine with an electric fan that dumped the dust into a pillowcase.

In 1908 Spangler sold the rights to a leather and saddle maker looking to diversify. Put on the market at (around £800 in today's money), the Hoover upright machine turned vacuum cleaners into a mass-market product.

I became determined to come up with a vacuum cleaner with a performance that did not stand or fall by the properties of a paper bag.

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