Christiaan Huygens was the first to discover a moon of Saturn, when he observed Titan on 25 Mar 1655. Working with his brother Constantijn, Huygens had developed a better way of making lenses which allowed him to make an improved telescope. Not wishing to reveal his discovery of the planet until he had confirmed his finding, Huygens made an anagram and presented it to his friends. Later, when he had confirmed his observations, he printed a tract, De Saturni Luna Observatio Nova in The Hague in 1656, where the meaning of the anagram was revealed.
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.
What Spinoza and Huygens Would Have Seen – a brief research and imagination of what Spinoza and Huygens would have seen if they looked together at the night sky on a mid-summer date, in the village of Voorburg in 1665.
Monconys’ Visit: Six Degrees of Separation for Spinoza – the importance of French diplomat Bathazar Moconys’ 1663 visit is fleshed out. This visit ties together some of the most signfiicant figures in Spinoza’s optical milieu, Hudde, Vossius, Huygens, (not to mention Vermeer at Delft) and attests to the pervasiveness of the single-lens, bead microscope design.
Simple or Compound: Spinoza’s Microscopes – A discussion of the conclusions that may be drawn from Christiaan Huygens’ 1668 admission that Spinoza is correct that smaller objective lenses produce finer representations of objects.
Spinoza’s Comments on Huygens’s Progress–letter 32’s observations on and objections to Huygens’ lens grinding machine are examined. Significant aspects of the Latin are retranslated, making more clear Spinoza’s point of emphasis, and opening of questions about whether Spinoza had extensive experience in polishing (or grinding) metal forms.
Spinoza’s Lens-Grinding Equipment– A commentary on the likely source types for Spinoza’s grinding laps, given those used by the Huygenses, with a rough assessment of Spinoza’s place in the milieu local knowledge.
To Understand Spinoza’s Letter 32 to Oldenburg– Various designs of Christiaan Huygens’s actual (and theoretical) lens grinding machines are shown to give better context to Spinoza’s description of, and objection to, the device he likely saw, as written about in letter 32. The issue of mechanistic complexity, the role of the craftsman, and Spinoza’s notion of liberation is broached.
Traces of Spinoza’s Microscope– Evidence is cited that Huygens primarily used melted bead lenses, and a diagram is presented from Huygens’s notebook which may represent design elements of Spinoza’s microscopes purchased at the auction of his estate.