Images of Stereographic Projections

Stereographic projections provide striking images: the heavens are displayed in two dimensions and constellations can be elaborately drawn. The engraved lines are impressive examples of the skill of instrument makers. But what can these images of stereographic projection tell us about how instruments were used?

Since the microscope was invented, just before 1600, people have been fascinated by the new world it allowed us to view. This section explains how people have interacted with that world. The Whipple Museum has a collection of over 400 microscopes and accessories, dating from the late 17th century to the present. Some of the most important microscopes in the collection were owned and used by famous scientists, such as Charles Darwin.

The articles in this section explain various aspects of the history of microscopy. Some of the most interesting stories concern the people who actually made and used microscopes. These 'associations' are emphasised throughout. Browse the articles using the links below or on the menu to the left of the page.

The 'Doctrine of the Sphere'

One of the hardest tasks for the historian of scientific instruments is the identification of precisely how instruments were used. In the case of stereographic projections the argument has frequently been made that they were used to teach astronomy, and specifically to teach either the Ptolemaic or Copernican systems. Whilst this is a tempting assumption, it has very little support from accompanying texts.

However, there is another tradition of astronomical teaching - not so closely related to natural philosophy or modern astronomy - that explains how stereographic projections were used in teaching. This was the 'Doctrine of the Sphere' the contents of which were:

"... the Horizon, Meridian, Aequator, Zodiack, Ecliptick, Tropicks, Poles of the World ... representing the model of the Universe." (1)

This part of astronomy concerned the description of the universe, but not in terms familiar to us. Grand debates about planetary systems were not as important as the practical concerns of navigation and horology.

The Doctrine also explained how the astronomical coordinates and lines of celestial globes related to those shown on terrestrial globes - this subject was called 'cosmography'. The image from Peter Apian'sCosmographi shows the relationship with a striking 'projected' woodcut print.

Images as instruments

Images of stereographic projections can also deepen our understanding of the use of instruments in a more general way: the common distinction made between books and instruments, and the ownership of both, doesn't hold when we examine such texts as John Collins' 1658 book The Sector on a Quadrant. Here we find that the plates were intended to be cut out and pasted on wood or brass and to be used as fully functioning instruments.

This point has been made before, in reference to the presence of moving volvelles in a great many renaissance and early-modern books.(2) These volvelles,showing such things as the phases of the moon, are instruments - at least in terms of function, if not form. Because of the division of historical material into libraries and museums, and the modern separation of the two into separate categories of study, research on texts and instruments is often divided artificially. From Collin's text, among others, we can see that books on instruments were often bought and used as instruction manuals, while the plates were made into working instruments.

Read more: the Gunter quadrant.