Hans Lippershey that time he became a master lens grinder and spectacle maker and established a shop. He remained in Middelburg until his death, in September 1619. Hans Lippershey is known for the earliest written record of a refracting telescope, a patent he filed in 1608. His work with optical devices grew out of his work as a spectacle maker, an industry that had started in Venice and Florence in the thirteenth century, and later expanded to the Netherlands and Germany. Lippershey applied to the States General of the Netherlands on 2 October 1608 for a patent for his instrument ""for seeing
Adriaan Anthonisz geometer and astronomer. Jacob Metius worked as an instrument-maker and a specialist in grinding lenses and applied for patent rights for the telescope a few weeks after Middelburg spectacle-maker Hans Lippershey tried to patent the same device. In 1585 Anthonisz discovered that the ratio of a circle's circumference to its diameter, later called pi, approximated the fractional value of . His son Adriaan Metius later published his father's results, and the value is traditionally referred to as Metius' number'. He is regarded as one of the first military engineers to apply the principles of the Dutch fortification system. Some of