PLAIN RULES WHICH WILL ENABLE ALL TO JUDGE

EXACTLY WHEN, AND WHAT

SPECTACLES

ARE BEST CALCULATED FOR THEIR EYES

OBSERVATIONS

ON

OPERA GLASSES AND THEATRES,

AND AN ACCOUNT OF THE

PANCRATIC MAGNIFIER,
FOR DOUBLE STARS, AND DAY TELESCOPES.

Qui Visum, Vitam dat."

By WILLIAM KITCHINER, M.D.

AUTHOR OF THE COOK'S ORACLE;
THE ART OF INVIGORATING AND PROLONGING LIFE;

THE PLEASURE OF MAKING A WILL;
OBSERVATIONS ON SINGING, &c. &c. AND

EDITOR OF
THE LOYAL, NATIONAL, AND SEA SONGS OF ENGLAND.

LONDON: PRINTED FOR HURST, ROBINSON, & CO. CHEAPSIDE; AND ARCHIBALD CONSTABLE AND CO. EDINBURGH.

1824.

The Illuminating and Magnifying Powers and Prices of

Newtonian, Gregorian, Cassegranian, und Herschelian Reflectors, and Galilean, Huygenian, and Achromatic Telescopes, of from 3 Inches to 7 Feet Focus, being Calculated and Described in Plain Terms which all Persons may easily understand..

To which will be added, An Appendix from the Writings of Sir Isaac Newton, Sir William HERSCHEL, &c. and Original Communications from Eninent Practical Opticians of the present time, on the Construction and Use of Telescopes.

LONDON:

PRINTED BY J. MOYES, GREVILLE STREET.

CONTENTS:

PAGE

BY

Preface, to be read after the Work........ 1

INTRODUCTION

2

SPECTACLES FOR THE POOR ....

10

CHAP, I. ON READING GLASSES FOR PER-

SONS WHOSE EYES ARE IMPAIRED

AGE; AND SINGLE EYE GLASSES FOR

THE SHORT-SIGHTED

12

II. SPECTACLES WITH PLAIN GLASSES 18

III. Cases Of PERSONS WHO COULD NOT

READ IN SPECTACLES .... 20 and 34

IV. HAND SPECTACLES

15 and 21

V. SYMPTOMS OF THE EYES REQUIRING

ŠPECTACLES TO READ WITH

23

VI. OF PRESERVERS....

29

VII. TABLE OF THE FOCAL LENGTH OF

THE MAGNIFYING GLASSES REQUIRED

AT VARIOUS AGES

33

The time that the First Glasses of 36

Inches focus will assist the Sight

sufficiently

37

VIII. WHEN TO

SPECTACLES

38

The Premature Use of Spectacles, how
pernicious to the Sight:.

32

IX. My GRANDMOTHER'S SPECTACLES.. 40

Spectacles for Gourmands

41

X. HINTS TO PERSONS CHOOSING SPEC-

TACLES

44

Divided Spectacle Glasses

48

Plan for Preserving the Sight

51

CHANGE

THE

FIRST

PAGE

57

79

FOR

AND

CHAP. XI. HINTS TO PERSONS BEGINNING TO

WEAR SPECTACLES; AND OF READING-

LAMPS AND CANDLESTICKS

Case of Dimness of Sight from Over-

exercise of the Eye

67

Of the Pole Star

67

Of the Double Ring of Saturn

69

Contents of the Second Part of the Eco-

NOMY OF THE EYES

71

Magnifiers for Artists

73

Concaves for reducing Miniatures 77

Nervous Dimness of Sight

78

Ointment for the Eye-lids

XII. PRECEPTS

IMPROVING

PRESERVING THE SIGHT

81

The Circumspector

84 and 200

Sight-Strengtheners for Painters, &c... 85

Double Rising Desk

87

Reading Candlestick ..

90

Green or Coloured Glasses

91

To keep Glasses perfectly clean ...... 93

XIII. GLASSES FOR SHORT-SIGHTED PER-

94

History of the Author's Case of Spec-

tacles

95

Invisible Opera Glasses

103

The Disadvantages and the Advantages

of being Short-sighted

104

XIV. SPECTACLE FRAMES

107

Silver Frames

107

Tortoise-shell Do.

107

Blued Steel Do.

107

The Length of the Bridge

Mean Distance between the Eyes 109

Width of a common Spectacle Frame.. 111

How many Tears shed Daily

111

SONS.

.. 109