(1.) 
Modern 
Advances 
in Science, 
(2.) 
Period 
1450-1550, 
(3.) 
Period 
1550-1650. 
DISSERTATION SIXTH. 
MATHEMATICAL AND PHYSICAL SCIENCE, 
CHAPTER I. 
INTRODUCTORY. 
§ 1. On the Plan of this Dissertation. 
Tue year 1850 may be said to complete the Third cen- 
tury of modern scientific progress, or the Fourth if 
we include its earliest dawn. To each of these ages 
of discovery may be assigned a peculiarity in the cha- 
racter of its improvements, and even in the methods 
which conduced to that improvement. 
Between 1450 and 1550 (a period so distinguished 
in letters and the arts), some great truths in physics 
and mathematics had presented themselves to a few 
precocious minds, yet they had not received any 
public acknowledgment, nor perhaps an adequate de- 
monstration. Algebra then first became a science. 
Leonardo da Vinci made the earliest steps since the 
time of Archimedes, in rational mechanics, and Co- 
pernicus almost at the close of this period promul- 
gated the true system of the world. 
But the next centenary (1550-1650) was the first 
of true scientific activity. Its characteristic feature 
was the vindication of observation and experiment as 
the prime essentials to the increase of natural know- 
ledge, with the consequent repudiation of the dogmas 
of the schoolmen, and the baseless methods of @ priori 
reasoning. The men of science formed a goodly array 
at this stirring time ; and signal were their triumphs. 
Galileo was beyond all comparison the glory of his 
age. His sagacity, his knowledge, his versatility of 
talent, his ingenuity as an inventor, his success in 
prosecuting his discoveries, and his zeal and elc- 
quence in making known their importance, gave him 
an enviable pre-eminence even amidst a mighty gene- 
ration. Bacon laid down the canons of a new method 
in philosophy which Gilbert and Kepler, as well as 
Galileo, had already acted on. Napier and Descartes 
prepared for the general application of mathematics 
in the coming struggle. 
The hundred years which next succeeded (1650- 
1750) saw the triumphant application of mathema- 7 
tics to Mechanics and Physics, and the establishment 
of the greatest mechanical theory of any age, that of 
Gravitation. The preparatory labours of a hundred 
and fifty years were brought, chiefly by the unparal- 
leled sagacity and genius of Newton, to a speedy and 
dazzling climax. His success brought numerous and 
worthy labourers into the field, but they found enough 
to do in gathering in the haryest which he had pre- 
pared for them. 
If we look for the distinguishing characteristic of  ( 
the centenary period just elapsed (1750-1850), we Period 
find it in this,—that it has drawn far more largely 
upon Experiment as a means of arriving at truth than 
had previously been done. By a natural conversion 
of the process, the knowledge thus acquired has 
been applied with more freedom and boldness to 
the exigencies of mankind, and to the farther in- 
vestigation of the secrets of nature. If we com- 
pare the now extensive subjects of Heat, Electri- 
city, and Magnetism, with the mere rudiments of 
these sciences as understood in 1750, or if we think 
of the astonishing revival of physical and experi- 
mental Optics (which had well nigh slumbered for 
more than a century) during the too short lives of 
Young and*Fresnel, we shall be disposed to admit 
1750-1850. 
