The Castle of Knowledge
The book is a sequence of four treatises that approximate in terms of presentation, to that found in the Pathway.The first treatise defines the terms used to describe the parts of earth and sky and of the sphere on which they are to be represented. Great care is exercised in choosing between authorities on these topics. The second treatise details the construction of solid and armillary spheres. The manufacture of these instruments is intended not only to consolidate the instruction of the previous treatise, but also to circumvent the need for knowledge of spherical geometry and trigonometry. The third treatise deals essentially with mapping of the celestial spheres onto a terrestrial sphere and is then used to deduce physical consequences such as climate, calendar, time and length of day. The fourth treatise deals primarily but not exclusively with Cosmographical matters, the model employed being that of Ptolemy. Alternative models are demolished by demonstrating their inability to explain experiential data. A similarly critical approach is adopted in assessment of the views of writers on the Ptolemaic model. Recorde’s calculations showed that he understood the implication of Copernicus’ theory, but was not prepared to commit to it. The major part of the text is used to up-date and correct Sacrobosco’s writings and displays many computations in the form of Tables.