WATCH AND CLOCK ESCAPEMENTS***

E-text prepared by Robert Cicconetti, Janet Blenkinship, and the Project Gutenberg Online Distributed Proofreading Team (http://www.pgdp.net/). Book provided by the New York University Library.

Note: Project Gutenberg also has an HTML version of this file which includes the original more than 180 illustrations. See 17021-h.htm or 17021-h.zip: (http://www.gutenberg.net/dirs/1/7/0/2/17021/17021-h/17021-h.htm) or (http://www.gutenberg.net/dirs/1/7/0/2/17021/17021-h.zip)

WATCH AND CLOCK ESCAPEMENTS

A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology

Compiled from the well-known Escapement Serials published in The Keystone

Nearly Two Hundred Original Illustrations

Published by The Keystone The Organ of the Jewelry and Optical Trades 19th & Brown Sts., Philadelphia, U.S.A.

1904

All Rights Reserved Copyright, 1904, By B. Thorpe, Publisher of the Keystone.

PREFACE

Especially notable among the achievements of The Keystone in the field of horology were the three serials devoted to the lever, cylinder and chronometer escapements. So highly valued were these serials when published that on the completion of each we were importuned to republish it in book form, but we deemed it advisable to postpone such publication until the completion of all three, in order that the volume should be a complete treatise on the several escapements in use in horology. The recent completion of the third serial gave us the opportunity to republish in book form, and the present volume is the result. We present it to the trade and students of horology happy in the knowledge that its contents have already received their approval. An interesting addition to the book is the illustrated story of the escapements, from the first crude conceptions to their present perfection.

CONTENTS

CHAPTER I.

THE DETACHED LEVER ESCAPEMENT 9

CHAPTER II.

THE CYLINDER ESCAPEMENT 111

CHAPTER III.

THE CHRONOMETER ESCAPEMENT 131

CHAPTER IV.

HISTORY OF ESCAPEMENTS 153

CHAPTER V.

PUTTING IN A NEW CYLINDER 169

INDEX 177

WATCH AND CLOCK ESCAPEMENTS

CHAPTER I.

THE DETACHED LEVER ESCAPEMENT.

In this treatise we do not propose to go into the history of this escapement and give a long dissertation on its origin and evolution, but shall confine ourselves strictly to the designing and construction as employed in our best watches. By designing, we mean giving full instructions for drawing an escapement of this kind to the best proportions. The workman will need but few drawing instruments, and a drawing-board about 15" by 18" will be quite large enough. The necessary drawing-instruments are a T-square with 15" blade; a scale of inches divided into decimal parts; two pairs dividers with pen and pencil points--one pair of these dividers to be 5" and the other 6"; one ruling pen. Other instruments can be added as the workman finds he needs them. Those enumerated above, however, will be all that are absolutely necessary.

[Illustration: Fig. 1]

We shall, in addition, need an arc of degrees, which we can best make for ourselves. To construct one, we procure a piece of No. 24 brass, about 5½" long by 1¼" wide. We show such a piece of brass at _A_, Fig. 1. On this piece of brass we sweep two arcs with a pair of dividers set at precisely 5", as shown (reduced) at _a a_ and _b b_. On these arcs we set off the space held in our dividers--that is 5"--as shown at the short radial lines at each end of the two arcs. Now it is a well-known fact that the space embraced by our dividers contains exactly sixty degrees of the arcs _a a_ and _b b_, or one-sixth of the entire circle; consequently, we divide the arcs _a a_ and _b b_ into sixty equal parts, to represent degrees, and at one end of these arcs we halve five spaces so we can get at half degrees.

[Illustration: Fig. 2]

Before we take up the details of drawing an escapement we will say a few words about "degrees," as this seems to be something difficult to understand by most pupils in horology when learning to draw parts of watches to scale. At Fig. 2 we show several short arcs of fifteen degrees, all having the common center _g_. Most learners seem to have an idea that a degree must be a specific space, like an inch or a foot. Now the first thing in learning to draw an escapement is to fix in our minds the fact that the extent of a degree depends entirely on the radius