24 January. In 1544, a solar eclipse was viewed at Louvain, which was later depicted in the first published book illustration of the camera obscura in use. Dutch mathematician and astronomer Reinerus Gemma-Frisius viewed a solar eclipse using a hole in one wall of a pavillion to project the sun’s image upside down onto the opposite wall. He published the first illustration of a camera obscura, depicting his method of observation of the eclipse in De Radio Astronomica et Geometrica (1545). Several astronomers made use of such a device in the early part of the 16th century. Both Johannes Kepler and Christopher Scheiner used a camera obscura to study the activity of sunspots. The technique was known to Aristotle (Problems, ca 330 BC).
The Leeuwenhoek display in the Oude Kerk, Delft. Except for an even smaller panel in the Prinsenhof, this seems to be the only display in Delft to commemorate the work of the ‘Father of Microbiology’. Surely his birthplace and hometown can do better than this for one of the great pioneers of Science?
Nicolaus Steno. Born 10 Jan 1638; died 26 Nov 1686.
(a.k.a. Niels Steensen, or Stensen) was a Danish geologist and anatomist who first made unprecedented discoveries in anatomy, then established some of the most important principles of modern geology. During medical studies in Amsterdam he discovered “Stensen’s duct” providing saliva from the parotid gland to the mouth. He was Danish royal anatomist for 2 years. Interested by the characteristics and origins of minerals, rocks, and fossils, he published in Prodromus (1669) the law of superposition (if a series of sedimentary rocks has not been overturned, upper layers are younger and lower layers are older) and the law of original horizontality (although strata may be found dipping steeply, they were initially deposited nearly horizontal.)
(1660) On instigation of Thomas Bartholin Steno first travelled to Rostock, then to Amsterdam and studied anatomy under Gerard Blasius, focusing again on the Lymphatic system. Steno discovered a previously undescribed structure, the “ductus stenonianus” (the duct of the parotid salivary gland) in sheep, dog and rabbit heads. A dispute with Blasius over credit for the discovery arose, but Steno’s name is associated with this structure.Within a few months Steno moved to Leiden. There Steno met the students Jan Swammerdam, Frederik Ruysch, Reinier de Graaf, Franciscus de le Boe Sylvius, a famous professor, and Baruch Spinoza. Also Descartes was publishing on the working of the brain, and Steno did not think his explanation of the origin of tears was correct. Steno studied the heart, and found out it was an ordinary muscle.
In 1667, Nicolaus Steno, a Lutheran, converted to Catholicism and became a major figure in the Counter-Reformation.
Johannes Fabricius. Born 8 Jan 1587; died c. 1615.
Dutch(sic) astronomer who was perhaps the first to observe sunspots. On 9 Mar 1611, at dawn, Johannes directed his telescope at the rising sun and saw several dark spots on it. He called his father to investigate this new phenomenon with him. The brightness of the Sun’s center was very painful, and the two quickly switched to a projection method by means of a camera obscura. Johannes was the first to publish information on such observations. He did so in his Narratio de maculis in sole observatis et apparente earum cum sole conversione. (“Narration on Spots Observed on the Sun and their Apparent Rotation with the Sun”), the dedication of which was dated 13 Jun 1611. He died aged 29.
I have recently added birthdays to the timeline, where all science related dates of importance have been marked in red. I am working on the student resources page, and I am still encouraging submissions in this area. I am also in need of copyright-free images which relate to Golden Age science, scientists or medicine. An image that would be quite useful to me would be the full image or images of Leeuwenhoek’s flea drawings.