Asked what the most valuable books in Trinity College are many people immediately think of the Book of Kells. Actually this is in four volumes, all of which are manuscripts, not books. The Old Library of TCD does, however, have ongoing exhibitions of its collection of early printed books. Currently the Long Room, the largest single-room library in the world, has on display several books of interest to historians of science.
Johann Gutenberg ushered in the era of moveable type in 1454 when he printed the 42-line Bible, and a copy of Gutenberg's New Testament is in the TCD library though not on display in the current exhibition of early printing carried out in German-speaking lands.
One of the most valuable books in the library is Peter Appian's Astronomicon Caesarium from 1540. This has pages with moveable parts, which can be used as a calendar. Appian was a renowned map-maker, and also the first to publish Pascal's triangle on the cover of a book in 1495.
In Astronomicon, Appian was the first westerner credited with noting that comets' tails point away from the sun. This lent support to the heliocentric theory, since if the Earth is the centre of the universe, comets' tails should point away from Earth. The Austrian George Joachim Rheticus in 1540 summarised the heliocentric or sun-centred model of Nicholas Copernicus. It was Rheticus who convinced the ailing Pole to publish, and in 1543 De Revolutionibus Orbium Colestium (On the revolutions of celestial bodies) appeared.
Dedicated to Pope Paul V, Copernicus's book included an anonymous preface by Andreas Osiander, a Lutheran minister. Probably because Martin Luther did not believe the Earth moved, Osiander said that the Earth did not move, but added that it was easier to calculate planets' positions if one assumed it did.
Though it is in the exhibition, Copernicus only got to see Osiander's preface when he was on his death-bed. A few hundred copies were printed. It was expensive and sold slowly but was reprinted in 1566 and 1617.
Also on display and of fundamental importance to science is De Humani Corporis Fabrica (On the structure of the human body) by Andreas Vesalius. It dates from 1543 and was the first widely available anatomy textbook.
Of particular interest are fabulous wood-cut illustrations attributed to the Flemish artist Stephen van Kalcar. Unlike Copernicus or Galileo, Vesalius published when he was 29. This book saw him accused of body-snatching and heresy, which effectively ended his research career.
The exhibition continues until mid-June.