Chapter VI: AN APPENDIX to the GEOMETRICAL AND GRAPHICAL ESSAYS, containing the

following Table by Mr. JOHN GALE, viz. a Table of the Northings, Southings, Eastings, and Westings to every Degree and fifteenth Minute of the Quadrant, Radius from 1 to 100, with all the intermediate Numbers, computed to the three Places of Decimals. Price 2s.

_In the Press, and speedily will be Published_,
LECTURES
ON NATURAL AND EXPERIMENTAL PHILOSOPHY,

In Five Volumes 8vo. The Second Edition, with upwards of Forty large Plates, considerable Alterations and Improvements; containing more complete Explanations of the Instruments, Machines, &c. and the Description of many others not inserted in the former Edition.

BY W. JONES, MATHEMATICAL AND PHILOSOPHICAL INSTRUMENT MAKER.

_ADVERTISEMENT._

_The editor esteems it his indispensable duty, to point out the several improvements which have been made in this work, in order to render it still more acceptable to the public._

_The whole has been carefully revised--many typographical errors corrected--numerous additions and emendations from the author’s own copy incorporated, and some superfluities rejected. Wherever any ambiguity occurred, the editor has endeavoured to elucidate the passage, observing due caution not to misconceive the idea which the author meant to inculcate. A more regular arrangement has been attempted, and occasional notes subjoined: in these, and in other parts of the work, it has been the editor’s primary object to ascertain facts, not to decide peremptorily. Should he in any instance have erred, he can assure the candid critic, that he shall experience a most sensible pleasure in conviction._

_The principal additions are_,

Accounts of the latest improvements which have been made in the
construction of microscopes, particularly the lucernal.

A description of the glass, pearl, &c. micrometers, as made by Mr.
Coventry, and others.

An arrangement and description of minute and rare shells.

A descriptive list of a variety of vegetable seeds.

Instructions for collecting and preserving insects, together with
directions for forming a cabinet.

A copious list of objects for the microscope.

A list of Mr. Custance’s fine vegetable cuttings.

_With respect to the plates, three new engravings are introduced,
viz._

PLATE IV. Exhibiting the most improved compound microscopes, with
their apparatus.

PLATE XIV. Microscopical figures of minute and rare shells.

PLATE XV. Microscopical figures of a variety of vegetable seeds.

_Many additional figures have been inserted in other plates, and a number of errors in the references corrected._

_A complete list of the plates and a more extensive index are also added._

_It has been generally understood, that the author intended to have published this edition in octavo; but, the impropriety of adopting that mode must appear evident, for the very reason assigned by the author himself in the concluding part of his preface. If the plates are liable to sustain damage by folding them into a quarto, they would have been subjected to far greater injury by being doubled into an octavo size, besides, being extremely incommodious for reference. As the work now appears, the purchaser may either retain the plates in the separate volume, or, without much inconvenience, if properly guarded, have them bound with the letter press._

_It affords the editor a pleasing satisfaction to mention, that notwithstanding the additional heavy expense incurred in the article of paper, &c. yet, by somewhat enlarging the page, and other economical regulations in the mode of printing, this edition is offered to the public at a trifling advance on the original price, though the improvements now made occupy considerably more than one-hundred pages._

_Anxious, lest the reputation which the work has already acquired, should be diminished by any deficiency on his part, the editor has sedulously applied himself to render it extensively useful to the serious admirer of the wonders of the creation; whether he has succeeded, is now submitted to the decision of the intelligent part of the public. He shall only add, that conscious of the purity of his intentions, and convinced of the instability of all terrestrial attainments, he trusts that he is equally secured from the weakness of being elevated by success, or depressed by disappointment._

_Apothecaries Hall, London,

Jan. 1, 1798._

CONTENTS.

CHAP. I.

A concise History of the Invention and Improvements which have been
made upon the Instrument called a Microscope. p. 1.

CHAP. II.

Of Vision; of the optical Effects of Microscopes, and of the Manner of
estimating their magnifying Powers. p. 26.

CHAP. III.

A Description of the most improved Microscopes, and the Method of
using them. p. 64.

CHAP. IV.

General Instructions for using the Microscope, and preparing the
Objects. p. 129.

CHAP. V.

The Importance of Natural History; of Insects in general, and of their
constituent Parts. p. 167.

CHAP. VI.

A general View of the internal Parts of Insects, and more particularly
of the Caterpillar of the Phalæna Cossus. A Description of sundry
miscellaneous Objects. p. 334.

CHAP. VII.

The Natural History of the Hydra, or Fresh Water Polype. p. 357.

CHAP. VIII.

Of the Animalcula Infusoria. p. 415.

CHAP. IX.

On the Organization or Construction of Timber, as viewed by the
Microscope. p. 574.

CHAP. X.

Of the Crystallization of Salts, as seen by the Microscope; together
with a concise List of Objects. p. 600.

CHAP. XI.

An Arrangement and Description of minute and rare Shells. A
descriptive List of a Variety of vegetable Seeds, as they appear when
viewed by the Microscope. By the Editor. p. 629.

CHAP. XII.

Instructions for collecting and preserving Insects. A copious List of
microscopic Objects. By the Editor. p. 665.

ADDITIONS. p. 713.

ERRATA.

Page 16, line 22, _for_ lead _read_ led

Page 20, line 6, _for_ Fig. T _read_ Fig. 1

Page 49, last line, _for_ usefully _read_ successfully

Page 62, last but one, _for_ stop _read_ stage

Page 80, line 22, _after_ microscope _add_ by

Page 88, three lines from bottom, _for_ improvent _read_ improvement

Page 95, line 2, _for_ R _read_ K

Page 111, two lines from bottom, _for_ VK _read_ VX

Page 115, line 12, _for_ g _read_ q

Page 125, note, _for_ Fig. 13 _read_ Fig. 13*

Page 145, line 17, _for_ cast of _read_ cast-off

Page 153, line 21, _for_ unkown _read_ unknown

Page 169, eight lines from bottom, _for_ is _read_ are

Page 188, note line 9, _for_ preventatives _read_ preventives

Page 195, line 7, _for_ exagon _read_ hexagon

Page 238, line 16, _for_ scarc _read_ scarce

Page 319, line 19, _for_ rise _read_ raise

Page 346, line 18, _for_ bread _read_ bred

Page 354, three lines from bottom, _for_ Fig. 1 and 2 _read_ Fig. 1
and 3

Page 445, line 18, _for_ immediate _read_ intermediate

LIST OF THE PLATES,

WITH REFERENCES TO THE PAGES WHERE THE SEVERAL FIGURES ARE DESCRIBED.

Plate Page

I. Various diagrams illustrative of vision and the optical
effect of microscopes 29