Perspective – Geometry – Instruction
The main concept of this book is to instruct the reader in certain topics dealing with geometric perspective, e.g. to provide an instruction in how to draw different architectural elements in proper geometric perspective.
The author, Johann Christoph Bischoff, starts with the “Vorrede”; a short general introduction to the topic of the book where he also illustrates his intentions and goals.
The main part of the book consists of the actual instruction. First, a brief description of 18 pages is given which also includes general rules of perspective drawing and geometry.
The following part is more practical. It includes 66 tasks (called “Aufgaben” by Bischoff) distributed on 116 pages.
Each of those tasks deals with a certain problem. Most of them are about how to get different objects into proper perspective. Some of them discuss quite simple geometric forms like a single square in the first or a square with a second one included in the second task. However, there are more complex ones throughout the book too which deal with actual architectural elements and situations instead of only geometric bodies. Task 12, e.g., is about getting the floor plan of a building into perspective, task 13 deals with the perspective of a garden and task 34 discusses the perspective drawing of buttresses and walls. Furthermore, Bischoff’s instructions, in addition to the ones on how to draw correctly, also include other topics, as e.g. rules and use of geometry in general. The tasks 17 to 22 discuss different topics, which are, among other things, about the height, length and depth of geometric objects.
The following part of the book, the appendix, is dedicated to colors. More precisely, it is, again, an instruction.
Here, the reader is instructed in how to prepare and use colors (“Von Zubereitung und Gebrauch der Farben”). This part covers 12 pages.
A register, following the appendix, then gives an overview of all terms being used in the book.
The book concludes with a series of illustrations that visualize the described procedure of the tasks in the main part of the book. Here one can see how the instructions are actually executed in practice.
What stands out in general is on the one hand the rigid and well-organized
structure of the single paragraphs which provide good orientation throughout the whole book. On the other hand there is also Bischoff’s very detailed and exact way of explaining things which can be seen particularly in the main part where each task is explained step-by-step.
Quote: The first three steps of the first task in the main part of the book as a general example;
“Die 1. Aufgabe.
Ein Quadrat in Perspektiv zu bringen.
1) Reisset ein geometrisches Quadrat a d c b, und ziehet darueber die Grund-Linie F C, und ueber diese die Horizont-Linie G E in einer beliebigen Hoehe.
2) Setzet auf die letztere den Aug-Punct O, und ziehet die Gesichts-Linien O D und O C.
3) Setzet auch auf die Horizont-Linie den Distanz-Punct E, auf die Grund-Linie aber die Seite des Quadrats d a, aus d in F, und ziehet die Linie F E.“