Cuar. V., § 5.] OPTICS.—SIR DAVID BREWSTER, 911 
(615.) To complete our biographical notice, we will here Mathematical Department (in which office he suc- Arago as 
ae just allude to M. Arago’s principal researches un- ceeded Fourier, in 1830), the duty devolved on him a ae of 
magnetic connected with optics, One was on the magneti- of writing the biographies of eminent deceased mem- demy of 
observa- zation of iron filings, and the formation of a tempo- bers of the Academy. He bestowed extraordinary Sciences. 
rary magnet, by means of a helical conductor of elec- 
tricity ;| the other was the important observation of 
the seeming magnetism of copper, and other non-mag- 
netic metals, when put in rapid rotation near a per- 
manent magnet. Neither of these happy experiments 
was carried out by their author. The former was left 
in the hands of Ampére, Sturgeon, and Henry; the 
latter was only rightly understood and valued when it 
was engrafted by Mr Faraday on his splendid series 
of researches on Magneto-Electric Induction,’ 
Arago is fairly entitled to be regarded as having 
proved the long-suspected connection between the 
aurora borealis and the freely suspended magnet ; and 
this in the face of urgent contestation. His contri- 
butions to Meteorology (founded rather upon the ob- 
servations of others than upon his own) were of con- 
siderable importance, and several of his popular pa- 
pers, appended to the smaller Almanac (Annuaire) 
of the Board of Longitude, contain a great deal of 
well-digested and curious information, 
As Secretary of the Academy of Sciences in the 
pains on these compositions, and strove to render 
them popular without sacrificing their scientific cha- 
racter, In this difficult attempt he was not always 
successful. Abrupt transitions, piquant anecdotes, 
paradoxical arguments, and political allusions, appear, 
at least to the English reader, to be unacademical 
adjuncts to the history of contemporary discovery. 
The special pleader is too often visible, and even the 
occasional sacrifices of the strong spirit of nation- 
ality by which he was commonly actuated, to some 
chivalrous adjustment of the rights of discovery, 
do not always carry conviction to the mind of the 
reader. The Eloge of Watt, probably the most po- 
pular, appears to us far from being the best of these 
biographies. Those of Sir W. Herschel and of Dr 
Young are ably executed, and display much research 
and candour. 
After having been for three years almost with- 
drawn from science by lingering disease, and nearly His death. 
complete blindness, Arago expired at the Observatory 
of Paris, on the 2d October 1853, aged 67.° 
§ 5. Smr DAviD BREWSTER—Progress of Experimental Optics—Laws of Polarization—Double 
Refraction produced by Heat and Compression—Discovery of Biaxal Crystals—Laws of Me- 
tallic Reflection—Absorption of Light; and Lines of the Solar Spectrum ; FRAUNHOFER.— 
Seebeck ; M. Bior. 
We have pleasure in ranking amongst the fore- 
most promoters of the science of optics in its sur- 
prising revival in the earlier part of this century, 
a philosopher who still lives amongst us and pur- 
sues with ardour the investigations of his youth. 
Sir Davin Brewsrer was born at Jedburgh, in 
the subject he then principally studied was rather 
connected with the use and theory of instruments than 
with physical optics in the sense in which we have 
explained it. This is evident from his first separate 
publication in 1813, “ on new Philosophical Instru- 
ments,” which, though containing many ingenious 
(520.) 
His early 
studies. 
Scotland, on the 11th December 1784. He was 
educated for the Scottish Church, and having en- 
tered the University of Edinburgh at a very early 
age, pursued his studies under Robison, Playfair, 
and Stewart, and formed the friendship of those 
and valuable suggestions, fell short of the importance 
of his subsequent publications, 
Sir David Brewster’s genius was first called forth (521.) 
by the announcement of Malus’s great discovery Directs his 
in 1808 of the polarization of light by reflection. aan 
eminent men. Amongst fellow-students, of no 
common distinction who at that time frequented the 
college lectures, and of whom not:a few were destined 
to signalize themselves in literature, science, and the 
career of politics, he formed the particular acquaint- 
ance of Mr, now Lord: Brougham, and through him 
was led to study the inflection of light, and to repeat 
Newton’s experiments. This was in 1799; nor did 
he afterwards lose sight of a science which he was 
so signally to improve. The distraction of other 
occupations, the calls of his profession, and his 
indifferent health prevented, however, any very 
constant application to optics: and the part of 
But for the unfortunate political relations of France optics. 
and England at the time, which prevented, to a 
degree which now appears almost incredible, the 
transmission of even the most interesting scientific 
facts from one country to the other, our country- 
men would have borne a larger share in the dis- 
coveries which immediately followed; and it would 
have been an easier task to apportion with his- 
torical accuracy what was due to each. As the 
French philosophers remained long in ignorance of 
the discoveries of Davy, and were anticipated in 
every important step in voltaic science, so Malus and 
Arago pursued and published researches and bril- 
1 See Electricity, § 4 
2 Electricity, § 5. 
* The article POLARIZATION oF Licu' in this Encyclopedia, the production of Arago, contains an excellent review of many 
»0f the topics of this Section. 
