Jansen, Zacharias

(b. The Hague, Netherlands, 1588; d. Amsterdam, Netherlands, 1628-1631)

optics.

As besieged Antwerp was about to fall to the Spaniards, Jansen’s parents fleld to Middelburg. From there they often traveled to nearby fairs, where the husband plied his trade as an optician. Thus it happened that Zacharias Jansen was born in The Hague in 1588, four years before his father died. His mother taught him how to manage his father’s shop in Middelburg, and on 6 November 1610 approved his marriage. His son, Johannes Sachariassen, was baptized on 25 September 1611.

Through his neighbor Willem Boreel (1591-1668), the mintmaster’s son, Jansen learned how to counterfeit Spanish copper quarters. Although the nominal penalty was death and confiscation of property, Jansen was merely fined on 22 April 1613 for for performing this patriotic act harmful to the former oppressors of the Dutch people. He moved to nearby Arnemuiden and escalated his counterfeiting to gold and silver coins. Condemned to death in 1618, he evaded the penalty by returning to Middelburg. There his first wife died in 1624, and in the following year he remarried. Sued for nonpayment of the interest on his mortgage, he leased a house in Amsterdam. His failure to meet the installment due on 1 May 1628 was followed by bankruptcy and auction of his property. On 17 April 1632 his son’s marriage banns described the bridegroom as fatherless.

Although twice convicted for counterfeiting, Jansen never pretended that he invented the telescope. Long after his death that false claim was made by his son on 30 January 1655, when the Middelburg authorities were taking testimony about the disputed invention to comply with the request of Willem Boreel, then Dutch ambassador to France. His request had been prompted by Pierre Borel, who was writing a book about the true inventor of the telescope.

In order to assert his father’s priority over all claimants, Johannes Sachariassen lyingly testified in 1655 that Jansen invented the telescope in 1590 (at the age of two!). Why 1590? Descartes’s friend Isaac Beeckman had visited Sachariassen’s shop in Middelburg to improve his lens-polishing technique. In 1634, before 30 April, Sachariassen privately told Beeckman that Jansen had made the first telescope in Holland in 1604, after an Italian model marked 1590. This had presumably been brought to Middelburg by one of the many immigrant Italian craftsmen.

BIBLIOGRAPHY

The invention of the telescope was wrongly attributed to Jansen by Borel, De vero telescopii inventore (The Hague, 1655-1656). Jansen’s actual contribution to the recognition and utilization of the telescope was discovered by Cornelis de Waard, De uitvinding der verrekijkers (The Hague, 1906), summarized in French by de Waard in Cielet et terre, 28 (1907-1908), 81-88, 117-124, English trans, by Albert van Helden. See also Antonio Favaro, “La invenzione del telescopio,” in Atti del Istituto veneto di scienze, lettere ed arti, 66 , pt. 2 (1906-1907), 19-46; Hendrik Fredrik Wijnman, “Sacharias Jansen te Amsterdam,” in Amsrelodamum, 20 (1933), 125-126; ibid., 21 (1934), 82-83;André Danjon and André Couder, Lunettes et télescopes (Paris, 1935), pp. 592-604; Journal tenu par Isaac Beeckman de 1604 á 1634, de Waard, ed., 4 vols. (The Hague, 1939-1953), I, 209; II. 210, 295; III, 249, 308, 376; Gerard Doorman, Patents for Inventions in the Netherlands During the 16th, 17th, and 18th Centuries, abridged English version (The Hague, 1942), pp. 71-72; J. H. Kruizinga, “De strijd om een Veerekijker,” in Historia, 13 (1948), 140-144;Hentry Charles King, The History of theTelescope (Cambridge, Mass., 1955), pp. vii, 30-33.

The portrait of Jansen in Borel was engraved by Jacob van Meurs after a drawing by Hendrick Berckman, who was in Middelburg in 1655 when the testimony concerning the invention of the telescope was being taken. Berckman drew Jansen’s portrait from imagination long after the subject’s death.

Edward Rosen