November 2008:
A test bid on the internet accidentally resulted in this transit. I was only one dollar above the reserve (which was quite low) and nobody was feeling like overbidding me (perhaps because of the world wide financial crisis?). Never mind, I am happy with this new addition!
October 2008:
Through a Dutch auction site I found myself these two bottles. Together they form a level instrument for hydrostatic levelling. Once bought by Corus for shaft alignment, they were discarded some 20 years ago and subsequently taken home by one of their employees.
September 2008:
Another Ebay item: Again after searching for it for several years I finally got myself a water bottle level. This is as basic as it can be; two communicating bottles of water, attached to eachother by a brass tube.
July 2008:
A lucky bid on Ebay: After searching for it for several years I finally got myself a Roelofs Solar prism for my Wild T2. Although of Dutch origin, this one came all the way from Fairbanks, Alaska. The Roelofs Prism can be used for sun shots, which in itself are used to determine true north in the field. In my case I use the Roelofs Prism for gyro calibrations. Using a simple spreadsheet on my mobile phone I get accuracies of about 0.005 degrees, which is more than enough for a proper calibration as the gyros that I calibrate (Fibre Optic Gyro's or FOG's) have an accuracy of about 0.3 degrees.
May 2008:
The Anual Study Conference of the Scientific Instrument Society was held in The Netherlands from 6th until 9th May, 2008. They not only visted several museums, but also had the chance to see the work of Tatjana van Vark in Ede and my instruments and dividing methods in Utrecht at the Utrecht University Museum (Picture by Otto van Poelje, Chair of the Oughtred Society Award, The Netherlands).
March 2008:
Last year I was commissioned to create a set of early 17th century navigational instruments for a new museum in Hirado, Japan. The set consitsed of a demi-cross, a cross-staff modelled after the one found on board of the Kronan, a traverse board and a chip log with hour glass.
November 2007:
Another reconstruction finished: Master Hood's cross-staff from 1590, the start of a new development in navigational instruments. This instrument has been described in period literature during the period 1590 - 1622 and was used for shadow observations of the sun in a forward manner and for land surveying.
Oktober 2007:
It is finally finished: the reconstruction of a 1625 demi-cross, an early Dutch backstaff after an instrument by Sir John Davis. This instrument has been described in period literature during the period 1625 - 1693 and was used for backward observations of the sun.
September 2007:
After a long period of no updates on my web site I finally have some news. To start with I found myself a new object: a Range Finder Cotton Type MKII by E.R. Watts & Son, London. This instrument was used some one hundred years ago to measure distance to objects at sea that have known dimensions. The other news is that since November last year I have been researching the development of the Davis Quadrant. During this research I stumbled upon blue-print like sketches of an instrument from 1625 called the Demi-Cross. With the reconstruction of it nearing it's completion I will soon upload a page on this instrument.
November 2006:
At the 2006 Navigational instruments as a source of historic information symposium at the National Maritime Museum in Greenwich I presented the spiegelboog (Mirror-staff in English) to an interested audience. On this picture by Jeremey Spencer I am explaining the instrument to Wouter Heijveld (Curator of Navigational Instruments Rotterdam Maritime Museum), Gloria Clifton (Head of Royal Observatory, Greenwich) and Richard Dunn (Curator of History of Navigation, National Maritime Museum, Greenwich).
September 2006:
Finally after two years of research a complete article on the spiegelboog (Mirror-staff in English) was published in the Bulletin of the Scientific Instruments Society. The Scientific Instrument Society (SIS) was formed in April 1983 to bring together people with a specialist interest in scientific instruments, ranging from precious antiques to electronic devices only recently out of production. The Society has a truly international membership offering those who join the chance to link up with instrument devotees across the world.
August 2006:
My latest find: a brass octant by T.S. & J.D. Negus, New York. In january 2007 I have been in contact with the great great granddaughter of John Davidson Negus. Much of the details on the Negus page originate from her research.
January 2006:
Delivered two cross-staffs to museums: one ebony cross-staff at the Archenhold Observatorium in Berlin, Germany and the copy of the Kronan cross-staff to the Kalmar Läns Museum in Kalmar, Sweden.
November 2005:
My latest project is finished: creating a copy of the Kronan cross-staff. In the meanwhile I'm starting research on another long gone navigational instrument: the early backstaff (not yet available on my site).
October 2005:
On the 22nd of October 2005 I presented a paper on the Reconstruction of the spiegelboog at the 'Who needs scientific instruments?' conference at museum Boerhaave in Leiden, The Netherlands. On the 11th we did a field test with my replica's.
September 2005:
My latest find: a Stadimeter. This instrument was used to measure the distance to ships at sea and is based on a sextant.
May 2005:
Combined my holiday with a visit to the Kalmar Läns Mmuseum where I met Lars Einarsson and Max Jahrehorn. They allowed me to measure the Kronan cross-staff which I will build later this year.
April 2005:
A project is finished: The reconstruction of a spiegelboog (Mirror-staff in English), an instrument by Joost van Breen. I also included a page where you can check if the staff in your possession is a spiegelboog or cross-staff.
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