The practice of isometrical perspective

Preface

When the Author ventured, in the month of March last, to point out to the readers of the Mechanics’ Magazine the very great utility of Isometrical Perspective, he had not the most distant thought of writing a Treatise on the subject; yet, when he was invited to do so, he did not hesitate to undertake the task, for, in the practice he had previously had, every difficulty that occurred was removed by perseverance; and he had then no idea that it would occupy so much time, cover so many pages, or require so many diagrams as have, it is hoped not without evident utility, been introduced.

It is, perhaps, unnecessary to say that the first idea of a Treatise on this subject was nothing like this which is now before the Public; nor will it be necessary to explain the progressive steps from the first plan to the last, or enume¬ rate the many diagrams from which the selection has been made.

As a person who is well acquainted with the locality of the streets, lanes, and courts of a city, does not find the same use in a map as a stranger, so it is possible that those who are previously well acquainted with perspective and projection might have applied this with no further explanation than is given by Professor Farish: but, while the Author begs to say that it is for -learners he has ven¬ tured to write, yet he trusts that in his investigation of this subject the more experienced will find something to

PREFACE.

induce them to use it, and in their practice to try to discover some useful application, and the most simple and direct methods for the representation of any particular object^ as well as to endeavour to ascertain other parti¬ cular facts.

In illustrating this subject, it would have been compa¬ ratively easy very greatly to have multiplied examples; but, while it is hoped that a sufficient number have been given to entitle it “a particular explanation” of the subject, it must be acknowledged that it is impossible to anticipate all the difficulties a learner may experience. Should any difficulties, however, occur, the draughtsman will find that, next to personal instruction, the best means of obtaining the information he may require is practice and perseverance. If he cannot accomplish his desire one way, let him try another: by this method he will soon discover that which is correct and most direct.

As most of the objects represented in this Treatise may be viewed in at least six distinctly different ways, the diagrams may be considered equivalent to about one thousand representations of different objects, and objects in different positions.

The intention of the Author has been to be as concise as possible, and to make such a selection of objects as would give the most comprehensive view of the subject within the space assigned. He hopes all the diagrams will be understood, and that he has introduced few or none but such as are essential, or whose places could not have been better supplied by others of more simple, natural, or obvious construction.

When the learner has drawn the several examples (and some of them to a larger scale) with the assistance of the

PREFACE.

O triangle, parallel ruler, scale of tangents, elliptical moulds, and proportional compasses, as the case may require, he will, it is hoped, be able to work out the representation of any other objects, however complicated. Even those who have already a knowledge of the subject will, probably, be surprised to find the facilities afforded by these instru¬ ments — especially the triangle, parallel ruler, and elliptical moulds — in representing objects with many and varying lines and surfaces.