Scheme of result of this attempt before the reader. 
802 
During the 
treatment Jengthened period of composition of this Dissertation— 
of the sub- 
ject. 
(4) 
protracted by indisposition and untowardcircumstances 
of differentkinds, I have had abundant leisure to reflect 
on the advantages and disadvantages of a plan which I 
had sketched in the previous paragraphs, at the very 
opening of my task. I am aware that a rigid criti- 
cism awaits every attempt like the present. J am 
aware also, that it is far easier to detect real faults, 
especially of omission, than to make sufficient allow- 
ance for the exceeding difficulty and delicacy of the 
undertaking. I have but one ground of confidence, 
and that is so strong, that I trust it will enable me 
calmly to meet every just critical reflection. I am 
conscious of having written in a spirit of absolute 
impartiality whether as regards persons or subjects, 
and that I have exercised to the full amount of my 
opportunities what powers of judgment I possess, 
I have striven to speak judicially and historically 
whether of friend or stranger, the dead or the living, 
Englishman or Foreigner. What I have felt the 
most constant effort, has been the needful exclusion 
of meritorious names, far more numerous than those 
especially included and dwelt upon in these pages. 
But this has appeared to me the cardinal point of 
my whole plan. ‘The labourers in science have been 
in these latter days so numerous, that had I noticed, 
even briefly, every one who had made a real step in 
science, my pages must have been crowded by names 
and titles of books. Even with the extension of bulk 
to which this essay has gradually and unavoidably 
grown (nearly double of its projected amount), the 
reader would rather have been bewildered than led by 
the perusal of such a catalogue. Besides, since such 
a brief historical synopsis forms very generally an in- 
troduction to the several articles of the Encyclopedia, 
to repeat it all here would have been but a tedious re- 
dundancy. No one conversant with such matters will 
imagine that I have saved myself any labour by this 
particularity of selection. On the contrary, it would 
have cost no effort to enumerate under each subject 
» the living or recently deceased authors upon it who 
are best known ; such a detail must have left a vague 
and shadowy impression on the mind of the general 
reader, and when regard is paid to the necessary limits 
of the essay, and the multitude of technical details and 
technical words which there is no space to define and 
illustrate, it is plain that the perusal must have been 
rendered as dry and unpalatable to those who seek 
general and elementary yet clear ideas, as it would 
have been tantalizing and unsatisfactory to the ac- 
complished student, or to the man of science in 
search of particular historical details. 
The end at which I have aimed is to select the 
more striking land-marks of progress in each subject 
in each age, and endeavour to connect them with the 
character and position of all the more eminent dis- 
MATHEMATICAL AND PHYSICAL SCIENCE. 
(Diss. VI. 
coverers, thus conveying to the general reader suffi- 
cient information on the limited number of particular 
subjects discussed, and interesting him not only in 
the science but in the individuals. Then, by a few 
slighter touches only, and the mention of some 
secondary names, to connect with one another these 
brighter periods of eminent progress, in which every 
country and every age feels a just pride. 
That by many I shall be considered to have dwelt 
too much on some eras of invention, and to have 
omitted others not less important, is a difference of 
judgment which it is impossible not to anticipate, 
but equally impossible to prevent. I will only add 
that I have endeavoured to extend my impartiality 
to subjects as well as to persons; and that I have 
not intentionally dwelt longer on the topics of my 
own predilection than on those naturally considered 
by other persons equally or more important. Many 
subjects as well as persons familiarly known to me 
are scarcely, if at all, mentioned in these pages. To 
leave some definite and vivid impressions, selected 
solely for their importance, on the mind of my reader, 
has been the great object constantly before me during 
the composition of this work. 
It will be seen from the preceding paragraphs, 
that I have deviated in some respects from the with thatof 
(15.) 
as.) 
scheme of my two distinguished predecessors in the the preced- 
composition of the Dissertations on Science, Professor ing Disser- 
Playfair and Sir John Leslie. The essay of the for- 
mer, which is the more finished and methodical, is 
admirably adapted to the period of the history of 
science of which he had principally to treat; the 
period, namely, of Galileo, Bacon, Newton, and 
Leibnitz. But the amount of material was smaller, 
and the principle of selection was also much simpler. 
The positive science of that age might almost be re- 
duced to two heads, Astronomy, including its mecha- 
nical principles, and Optics. It was an age not more 
distinguished for the Truths it disclosed, than for 
the invention and right appreciation of the Methods 
of Discovery. Inductive Logic, and Mathematical 
Logie applied for the first time to dynamics, very 
justly claimed a place in a dissertation on the pro- 
gress of science, in a period when these preliminary 
doctrines and discoveries were the stepping stones by 
which even the basement story of the Temple of 
Nature could alone be reached. The Philosophy of 
Bacon and the discovery of Fluxions, occupied there- 
fore, with much reason, a large portion of Professor 
Playfair’s beautiful Dissertation ; and it is impossible 
to regret that an intellect so admirably qualified for 
tracing and displaying the intimate and historical 
connection of branches of knowledge so varied in 
their principles and character, should have been thus 
congenially employed, to the delight and edification 
of readers of every degree of acquirement from the 
highest to the humblest.! 
1 In mentioning the name of my distinguished predecessor in the Chair of Natural Philosophy in the University of Hdin- 
burgh, I willingly take the opportunity of noticing, in a few words, his peculiar merits, to which the Dissertation contained in 
tations. 
