LIGHT SCIENCE.
LONDON: PRINTED BY
SPOTTISWOODE AND CO., NEW-STREET SQUARE
AND PARLIAMENT STREET
A SERIES OF FAMILIAR ESSAYS
ON
SCIENTIFIC SUBJECTS, NATURAL PHENOMENA, &c.
BY
RICHARD A. PROCTOR,
AUTHOR OF ‘THE SUN’ ‘OTHER WORLDS THAN OURS’ ‘SATURN’ ETC.
NEW EDITION.
LONDON:
LONGMANS, GREEN, AND CO.
1886.
In preparing this edition, only those passages whichhave been shown by recent researches to be erroneoushave been removed. It has not been thought necessary,or even desirable, to modify the wording of Essays(by changes of tense or otherwise) in such a way that,as thus modified, the Essays might have appeared in1884. In many cases this would have been altogethermisleading, whereas, with the dates prefixed to theseveral Essays, no misconceptions can arise.
Richard A. Proctor.
vi
This edition has been carefully revised, and, in parts,considerably modified. Thus the Essay on Britain’sCoal Cellars has been added, and two Essays on GovernmentAid to Science have been removed. I may mentionthat my views on the subject of the last-namedEssays have changed altogether since those Essays werewritten—certain circumstances which have come undermy observation having convinced me that more mischiefthan advantage would result from any wide scheme forsecuring Government aid for scientific researches.
Richard A. Proctor.
London: January 1873.
vii
In preparing these Essays, my chief object has beento present scientific truths in a light and readableform—clearly and simply, but with an exact adherenceto the facts as I see them. I have followed—here andalways—the rule of trying to explain my meaningprecisely as I should wish others to explain, to myself,matters with which I was unfamiliar. HenceI have avoided that excessive simplicity which someseem to consider absolutely essential in scientific essaysintended for general perusal, but which is often evenmore perplexing than a too technical style. The chiefrule I have followed, in order to make my descriptionsclear, has been to endeavour to make each sentencebear one meaning, and one only. Speaking as areader, and especially as a reader of scientific books, Iventure to express an earnest wish that this simplerule were never infringed, even to meet the requirementsof style.
It will hardly be necessary to mention that severalof the shorter Essays are rather intended to amusethan to instr