Part 1

THE MAGIC LANTERN

AND ITS MANAGEMENT.

THE MAGIC LANTERN

AND ITS MANAGEMENT

INCLUDING

FULL PRACTICAL DIRECTIONS FOR PRODUCING THE LIME LIGHT, MAKING OXYGEN GAS, AND PREPARING LANTERN SLIDES

T. C. HEPWORTH

LATE LECTURER ON SCIENCE TO THE ROYAL POLYTECHNIC INSTITUTION, LONDON.

London CHATTO AND WINDUS, PICCADILLY 1885 [All rights reserved]

PREFACE.

During the past few years, the introduction of a dry-plate photographic process of such a nature that it can be practised successfully by amateurs of both sexes has aroused an amount of interest in the camera and its capabilities, such as few scientific instruments can command. The Magic Lantern is now closely allied with the camera, for there is no means of showing the perfection of a photographic picture so well as by its aid. But many persons are deterred from adopting the latter contrivance because they fancy that there must be innumerable difficulties to surmount before they can hope to master its management. It is for these that the following pages have been written, in which I have tried to place clearly before the reader what can be done, and how to do it. I have also tried to indicate the educational value of the lantern, and have pointed out in a necessarily brief manner how various branches of knowledge can be illustrated by its aid. The numerous personal inquiries addressed to me after my lectures, and the numbers of letters constantly received, asking for information regarding the lantern, its management, and the preparation of lantern slides, have convinced me that there is room for a manual, humble though it be, dealing with these subjects.

T. C. HEPWORTH.

32, CANTLOWES ROAD, LONDON, N.W.

CONTENTS.

THE HISTORY OF THE MAGIC LANTERN.

PAGE

The introduction of mineral oil lanterns.--The advance caused by the aid of photography.--The optical system of a modern lantern.--Educational value of the lantern 1-12

THE LIME-LIGHT.

Different forms of lime-jets.--Precautions to be observed in their use 12-16

DISSOLVING VIEWS.

The old method and the new.--The biunial lantern.--The dissolving-tap and its management.--Coincident discs.--‘Effects’--The application of the double lantern to spectrum analysis 17-22

MAKING OXYGEN GAS.

Necessary precautions.--The purifier.--Explanatory diagram.--Practical details.--The retort.--The gas-bag.--Iron bottle for compressed gas.--Pressure-boards. --Lime cylinders 22-33

THE SCREEN OR SHEET.

Arrangement adapted to a sitting-room.--Public exhibitions. --Method of hanging a large sheet.--Sheets on frames 33-37

PICTURES FOR THE LANTERN.

Photographic slides.--Home-made pictures.--Drawing pictures on ground-glass.--The slide-painter’s easel.--Mounting slides 37-43

ON THE COLOURING OF PHOTOGRAPHIC TRANSPARENCIES.