In the summer of 1645, the Oratorian Virgilio Spada (1596–1662) acquired a painting of a debate on astronomy by the Sienese artist Niccolò Tornioli (1598?–1651) and displayed it in the Palazzo Spada, the Roman residence of his older brother, Cardinal Bernardino Spada (1594–1661). Our discussion of The Astronomers questions some of the traditional identifications of its characters, although we cannot claim to have solved these figures’ identities and several remain a mystery. We do present new iconographic interpretations of particular scientific instruments, diagrams, and natural phenomena in the canvas. These novel readings occasionally remain conjectural in part because Tornioli represents these entities in a way that makes it clear that he did not fully comprehend them. The errors and obscurities in Tornioli’s painting lead us to two conclusions. First, that the erudite Virgilio Spada was unlikely to have been involved in the definition of the painting’s iconographies, as he would have objected to Tornioli’s crass mistakes and obscure imagery. Second, that these errors and indistinct details should be taken at face value, insofar as they accentuate the difficulties of astronomical observation. Beyond highlighting these challenges, we argue that the painting also visualizes techniques for countering them. Specifically, the canvas would have focused early modern observers’ attention on the edifying powers of civil conversations and communal observations with scientific instruments as well as images—including diagrams, celestial maps, and paintings.

This is a story of the impact a collector can have on creating one of the world’s most celebrated of specialized museums. The museum is Harvard University’s Collection of Historical Scientific Instruments and the man responsible is David P. Wheatland of Topsfield, Massachusetts.

The publisher's print version is attached as a PDF.  The web version of the essay is here.

Tim’s Vermeer is a recent documentary feature film following engineer and self-described non-artist Tim Jenison’s extensive efforts to “paint a Vermeer” by means of a novel optical telescope and mirror-comparator procedure. His efforts were inspired by the controversial claim that some Western painters as early as 1420 secretly built optical devices and traced passages in projected images during the execution of some of their works, thereby achieving a novel and compelling “optical look.” We examine the proposed telescope optics in historical perspective, the difficulty and efficacy of the mirror comparator procedure as revealed by an independent artist/copyist’s attempts to replicate the procedure, and the particular visual evidence adduced in support of the comparator hypothesis. Specifically, we find that the luminance gradient along the rear wall in the duplicate painting is far from being rare or difficult to achieve, as was claimed; in fact, such gradients appear in numerous Old Master paintings that show no ancillary evidence of having been executed with optics. There is indeed a slight bowing of a single contour in the Vermeer original, which one would nominally expect to be straight; however, the optical explanation for this bowing implies numerous other lines would be similarly bowed, but in fact all are straight. The proposed method does not explain some of the most compelling “optical” evidence in Vermeer’s works, such as the small disk-shaped highlights, which appear like the blur spots that arise in an out-of-focus projected image. Likewise, the comparator-based explanations for the presence of pinprick holes at central vanishing points, and the presence of underdrawings and pentimenti in several of Vermeer’s works, have more plausible non-optical explanations. Finally, an independent experimental attempt to replicate the procedure fails overall to provide support for the telescope claim. In light of these considerations and evidence we conclude that it is extremely unlikely that Vermeer used the proposed mirror-comparator procedure.

Appendix III to “The Scientific and Historical Value of Annotations on Astronomical Photographic Plates”

The Scientific and Historical Value of Annotations on Astronomical Photographic Plates

Authors: Sara J. Schechner, David H. Sliski
Comments: 46 pages, 9 figures, Published in the Journal for the History of Astronomy, February 2016

arXiv:1602.03475v2 [physics.hist-ph]
DOI: 10.1177/0021828615624094
License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Subj-class: History and Philosophy of Physics (physics.hist-ph)

The application of photography to astronomy was a critical step in the development of astrophysics at the end of the nineteenth century. Using custom-built photographic telescopes and objective prisms, astronomers took images of the sky on glass plates during a 100-year period from many observing stations around the globe. After each plate was developed, astronomers and their assistants studied and annotated the plates as they made astrometric, photometric and spectroscopic measurements, counted galaxies, observed stellar variability, tracked meteors, and calculated the ephemerides of asteroids and comets. In this paper, the authors assess the importance of the plate annotations for future scientific, historical, and educational programs. Unfortunately, many of these interesting annotations are now being erased when grime is removed from the plates before they are digitized to make the photometric data available for time-domain astrophysics. To see what professional astronomers and historians think about this situation, the authors conducted a survey. This paper captures the lively discussion on the pros and cons of the removal of plate markings, how to best to document them if they must be cleaned off, and what to do with plates whose annotations are deemed too valuable to be erased. Three appendices to the paper offer professional guidance on the best practices for handling and cleaning the plates, photographing any annotations, and rehousing them.

Three supplementary appendices are available online here.

The Leyden jar was arguably the most important instrument for electrical experiments in the second half of the 18^th century, and Benjamin Franklin’s fame as a natural philosopher was based largely on his explanation of how it worked.   In two remarkable letters written in the 1750s to scholars in Boston, Franklin offers instruction on the making of Leyden jars and assembling them into batteries.  The letters also illustrate the challenges of getting and maintaining natural philosophical apparatus in colonial America, and a culture of recycling goods in order to make do.