The collected works of James Mac Cullagh

428 Pages·1880·15.489 MB·English

by  James Mac Cullagh

PRESENTED
The University of Toronto
The Johns Hopkins University
BALTIMORE

Digitized by the Internet Archive
in 2007 with funding from
IVIicrosoft Corporation
http://www.archive.org/details/collectedworksOOmaccuoft
THE COLLECTED WORKS
OF
JAMES MAC CULLAGH,
LL.D.

DUBLIN UNIVERSITY PRESS SERIES
THE COLLECTED WORKS
OF
JAMES MAC CULLAGH,
LLD.,
FELLOW OF TRINITY COLLEGE,
AND
PROFESSOR OF NATURAL PHILOSOPHY IN THE UNIVERSITY OFDUBLIN.
EDITED BY
JOHN H. JELLETT, B. D.,
AND
SAMUEL HAUGHTON, Clk., M.D.
DUBLIN: HODGES, FIGGIS, & CO., GRAFTON-STREET.
LONDON LONGMANS, GREEN, & CO., PATERNOSTER-ROW
:
i88o.
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DUBLIN
:
PRINTED AT THE UNIVERSITY PRESS.
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PREFACE-.
The present volume contains a complete collection of
the scientific works of the late Professor Mac Cullagh.
They have been reprinted for the most part from the
Proceedings and Transactions of the Royal Irish Aca-
demy, in which they originally appeared. Some few
have been taken from the Philosophical Magazine.
Prof. Mac Cullagh's most important contributions
to Science were made in the departments of Physical
—
Optics and Geometry the first class being very much
the larger. The discrepancy is not, however, as great
A
as might at first sight appear. considerable part
of his Optical researches, more especially those of
earlier date, really belong to the domain of Geometry
and, if they were so classed, the inequality between
the classes would be much reduced. Such a classifica-
tion, however, involving the separation of the purely
geometrical propositions from their physical applica-
tions, would be exceedingly- inconvenient, and these
propositions have been allowed to remain in the con-
nexion in which the author placed them.
b
iv Preface.
In his earlier Optical 'Memoirs, Prof. Mac CuUagh
aimed chiefly at elucidating, by means of geometrical
theorems, the physical theory of Fresnel. This is the
principal object of the Memoirs I.-IV. in the present
volume. In V. occurs the first notice of a problem
which subsequently occupied so large a space in Prof.
Mac Cullagh*s researches, namely, the investigation
of the laws according to which polarized light is re-
flected and refracted at the surface of a crystalline
medium. This problem is discussed at length in XI.
and XIV. In the former of these memoirs he deduces
a solution of the problem from certain assumed phy-
sical principles. In the second he seeks to establish
the theoryupon a strictly mechanical basis by means of
the general dynamical equation of Lagrange. These,
whichare the principal memoirs treating ofthe general
question, are supplemented by Memoirs XVI.—XIX.,
in which the same problem is discussed. Two other
important questions, namely, metallic reflexion and the
double refraction of quartz, which required a peculiar
mode of treatment, are considered in Memoirs VI.,
VII., XV., XVII., XXI.
Prof. Mac Cullagh's contributions to pure Geo-
metry, excluding, as has been said, all those theorems
which have been introduced by the author as auxiliary
to his Optical researches, form the second Part of the
present volume. The first of these is a Memoir on