148 MALUS. 
and Biot. The report was presented by Lagrange, and 
thus nothing was wanting duly to signalize the important 
discovery of Malus. 
DISCOVERY OF POLARIZATION BY REFLEXION, 
We must go back to Erasmus Bartholimus to find the 
first observations relative to the existence of double 
refraction in Iceland spar, also called cale spar, or rhom- 
boidal carbonate of lime. Huyghens had occupied him- 
self with the study of these phenomena, and pointed out 
a geometrical construction of a very simple and elegant 
kind by which we can determine, in all directions and at 
all incidences, the position of the extraordinary ray rela- 
tive to the ray properly called the ordinary ray, whose 
position is determined by the well-known law of the 
sines, made known by Descartes. Huyghens arrived at 
the discovery of this construction by means of an ellip- 
soid, which, as he tells his readers, he derived from con- 
siderations borrowed from the theory of waves. 
The reporter of the Academy on Malus’s memoir of 
the 12th December, 1808, entitled Memoir on a Prop- 
erty of Light reflected by transparent Bodies, who was 
no other than Laplace, wished that Huyghens had been 
contented to have given his law as the result of experi- 
ence only. But I may be permitted to ask, Is not the 
hatred of theory carried too far when it leads to the sug- 
gestion of dissimulation or the want of sincerity ? 
Newton contended for substituting other rules instead 
of that of Huyghens; but these have not been found 
conformable to facts. 
Among modern observers, Wollaston was the first who 
established the truth of the principles laid down by the 
Dutch philosopher. To make this verification he availed 
. 
