(542.) 
His other 
scientific 
papers. 
(543,) 
916 
which we owe to his genius. It is an analysis of the 
coloured light of the (so-called) homogeneous rays of 
the pure spectrum by the specific action of absorbing 
substances. Sir D. Brewster believes that he has 
separated the homogeneous orange of Newton into 
red and yellow, the green into yellow and blue; and 
that, in fact, each of the three primary colours exists 
at every point of the spectrum. But as grave doubts 
have been thrown on the results, especially by the 
recent careful experiments of Helmholz, I shall not 
further insist upon them here.? Still less can I take 
notice of a multitude of microscopic researches on a 
variety of objects in the animal, vegetable, and mineral 
kingdom, and on the physiology of vision, with which 
Sir D. Brewster has filled a multitude of memoirs, 
each bearing testimony to the zeal and acuteness by 
which his researches are directed. 
Sir David Brewster received, in 1816, jointly with 
Seebeck, one of the great prizes of the Institute; he 
also received, in succession, all the medals in the gift 
of the Royal Societies of London and Edinburgh, and 
he is an honorary member of the principal academies 
of Europe. In particular, he is one of the eight asso- 
ciate-members of the French Academy of Sciences. 
To meteorology he has been a valuable contributor, 
having discussed in an able paper the law of the 
distribution of temperature over the globe, and 
pointed out the near coincidence of two regions 
or centres of greatest cold in the northern hemi- 
sphere, with the magnetic poles. His papers are 
so numerous, and their variety is so great, as to 
render an enumeration, even of those containing what 
may reasonably be termed discoveries, impossible 
within our limits. Few persons have made with 
their own eyes so vast a number of independent 
observations ; few have ever observed better, or re- 
corded their observations more faithfully. He has 
discovered (as we have partly seen) a multitude of 
laws of phenomena of the greatest importance in the 
construction of a theory, but he has not been forward 
in proposing such a theory. Neither the moveable 
polarization of Biot, nor the transverse undulations 
of Young and Fresnel, received his cordial assent. 
Generally speaking, he has been favourable to a cor- 
puscular theory of light, without, however, attempting 
to render the Newtonian view mechanically consistent 
with the astonishing variety of complex phenomena 
which he aided in discovering, and which would evi- 
dently require it (to say the least) to be completely 
remodelled. His scientific glory is different in kind 
from that of Young and Fresnel; but the discoverer 
of the law of polarization, of biaxal crystals, of op- 
tical mineralogy, and of double refraction by com- 
pression, will always occupy a foremost rank in the 
intellectual history of the age. 
Before closing this section I shall add a few words 
respecting the discoveries of MM. Seebeck and Biot, 
MATHEMATICAL AND PHYSICAL SCIENCE. 
[Diss. VI. 
which have a very close relation to those of Sir David 
Brewster. 
Tuomas Seepeck was born in 1770. We have 
(544.) 
seen that he was one of the discoverers cf the depola- Seebeck. 
rizing structure of heated and compressed glass (527). 
In 1816 he observed, independently of M. Biot, the 
property of oil of turpentine and other fluids to rotate 
the plane of polarization of light transmitted through 
them, thus acting similarly to a crystal of quartz on a 
ray passing along its axis (512), Previously to these 
discoveries he had repeated Sir William Herschel’s 
experiment on the position of maximum heat in the 
spectrum, and found it to vary with the material of 
the prism. When the science of electro-magnetism 
was created by Oersted in 1819, his attention became 
chiefly directed to that class of phenomena, and in 
1823 he was fortunate enough to discover thermo- 
electricity. He also wrote many papers on allied 
subjects. He was a skilful observer, but deficient in 
the power of physical analysis. He died in 1831. 
M. Biot, at the time I write, the oldest member 
(I believe) of the Academy of Sciences, and one of M- Biot— 
his nume- 
. 
the veterans of European science, was born at Paris 
(545.) 
rous re- 
in 1774, and has lived to the age of 80, a life of searches. 
almost unintermitted intellectual labour. It is im- 
possible not to be touched by the evidence of such 
unconquerable love of knowledge. He was, if I 
mistake not, one of the original pupils of the Poly- 
technic School; and his talents being first developed 
in an almost purely mathematica] direction, he at- 
tracted the notice of Laplace, who introduced him to 
the Institute, and by whom he was always befriended. 
In 1802 he published a work on curves and surfaces 
of the second degree, and was the first after Lambert 
who thought of applying mathematics to the theory 
of conducted heat. From this time his attention 
was almost exclusively directed to the applied sciences, 
and the number and variety of his experiments and 
writings almost baffles enumeration. Descriptive and 
practical astronomy, the theories of sound, of light, 
of the voltaic pile, of terrestrial magnetism, of electro- 
magnetism, of heat, radiant and combined, have been 
the subjects of his studies and writings. We find him 
in the earlier part of his career associated with Gay 
Lussac in his first aeronautic expedition, and with 
Arago in the geodetical and astronomical operations 
of the great arc of the meridian. He afterwards 
carried the pendulum to the Island of Unst, the 
northmost land in Shetland; and he made original 
experiments on the propagation of heat and of sound. 
He wrote a voluminous treatise on descriptive and 
practical astronomy, one still more elaborate on 
general physics, and a vast number of miscellaneous 
papers in the Journal des Savans and the Biographie 
Universelle. His original memoirs in the Trans- 
actions of the Academy are usually very long and 
elaborate, his calculations and empirical formule 
1 See Sir D. Brewster’s stat t and deft 
of his opinions in his Life of Newton, vol. i., p. 117, &e. 
