When were cell phones invented&who were they made by?

Answer Martin Cooper invented the cell phone in 1973, and Motorola was its maker. The phone was much bigger and heavier than today's models. Called the DynaTAC, the phone did not go one sale until 10 year... Read More »

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When were pulleys invented?

Like many ancient machines, no one knows exactly when pulleys were invented or by whom. Archimedes, who lived from 287 B.C. to c. 212 B.C., may have been the inventor of the first block and tackle... Read More »

When were intercoms invented?

In the 1850s French inventor/magician Jean Eugene Robert-Houdin developed the first intercom-like device for use in his home. In 1894 the first patent for an office intercom system, the Kellogg Int... Read More »

When were lie detectors invented?

The first lie detector was invented by Cesare Lombroso in 1895. This device, named plethysmograph, was very different than the polygraph used today. The plethysmograph simply monitored blood flow a... Read More »

When were arrowheads invented?

The earliest arrowhead is believed to be one made of bone, discovered at Sibudu Cave on the north coast of South Africa. It dates from the Paleolithic Era and is believed to be over 61,000 years ol... Read More »