In addition to the image and description of Regiomontanus’s discussion on Ptolemy’s instrument - the meteoroscope - the book contains the earliest printed illustrations and instructions for creating and operating an instrument known as 'The Cross' or 'Jacob’s Staff'. This instrument became the primary method for Portuguese and other European explorers to measure the angles between stars from the sixteenth century well into the nineteenth century.

Werner also adds to Claudius Ptolemy’s '

' discussions on four different map projections including stereographic (polar) projections and his eponymous Werner equal-area projection, which uses a cordiform (heart-shaped) map projection to preserve distances along meridians. His additions are also notable for describing the concept of the lunar distance method for determining longitude, a method first suggested by Amerigo Vespucci.

Binding: Nineteenth-century armorial bookplate on front pastedown (perhaps German), later elaborately blind-stamped pigskin with metal hinges, raised bands and gilt spine label, marbled endpapers, red stained edges, clasps lacking, minor worming to spine.

Collation: Folio. 277 pages. Sixty-eight leaves with seventy-five woodcut diagrams, three of them full-page; occasional early manuscript annotations throughout.

’s 1514 translation of Claudius Ptolemy’s '

' is a major landmark in the history of mathematical geography and scientific cartography. It was highly influential to map makers and astronomers, including 

, for over two centuries after its publication. 

Werner's work is significant because it was the first direct translation of the '

' from the original Greek, rather than from a Latin or Arabic translation. It is also important because it features Werner’s additions to Ptolemy’s text. Among these additions are four new maps, including one of his own design: a equal-area projection in a cordiform, or heart-shape, projection. Werner also included an important description and illustration of a meteoroscope - a device developed by Ptolemy and revived by Regiomontanus which is used to help calculate the position of stars. 

' is a souvenir of the rapid copying culture of the work of Claudius Ptolemy. This began just a century earlier with Jacobus Angelus’ Latin translation of 1406–7. Werner’s translation instead referenced a Greek edition, which provided him fertile ground to inlay his own original commentary on Ptolemy’s material. This included a discussion based on Johannes Regiomontanus’s letters on Ptolemy’s meteoroscope, which was the first appearance of these works.

Diagram of Ptolemy's 1st projection

Diagram of Ptolemy's 2nd projection

Circular diagram 

Charts and semi-circular diagram 

Quadrant of a sphere diagram 

Geometry within a semi-circle 

Wind  chart

Triangular geometric diagrams

Circular diagrams

Werner's Cordiform projection

Projection grid from a single point

Globe projection from a single point

Circular projection / Oval projection 

Armilliary sphere

Werner makes remarkable additions to Ptolemy’s '

' in the form of four different map projections, including stereographic (polar) projections and his eponymous Werner equal-area projection, which uses a cordiform (heart-shaped) projection to preserve distances along meridians.