BRITISH ASSOCIATION MEETING. 
451 
generation, so extinction has been concomitant witli creative power, 'which has 
continued to provide a succession of species; and so far as the varying forms of 
life wliich this planet has witnessed, there has been an advance and progress in 
tlie main. 
Geology demonstrates that the creative force has not deserted this earth during 
any of her periods of time, and that in respect to no one class of animals has the 
manifestation of that force been limited to one epoch. 
In the reflection that at how late, and in how brief, a period of historical time, 
geological knowledge has been acquired, we must feel that, vast as it seems, it 
may be but a very small part of the patrimony of truth destined for the possession 
of future generations. 
Comparing the realities of the Association in its labours with the " Solomon's 
House" of the " New Atlantis," and the realities of our jiational and private 
observatories, our museums, our learned societies, and zoological, botanical, and 
horticultual gardens with its imaginary departments, it seems as if we were realising 
that grand philosophical dream, or prefigurativc vision of "the father of modern 
science." We can scarcely appreciate the rate of pi'ogress of human knowledge 
unless we go back for an instant to that period which is thus chosen as the 
starting-point of this survey. 
From Bacon's treatment of the Copornican theory we are passed onwards to 
Galileo's invention of the telescope and the discovery of the four sm.all moons 
revolving round Jupiter, the analogy of which to the Solar system as conceived by 
Copernicus, gave the " holding-turn" to the opinions of mankind respecting the 
heliocentric system ; and hence we are progressed through the first observations 
of the transits of Mercury and Venus across the sun's disk, and those other 
observed facts upon which the motions of the heavenly bodies have been deter- 
mined and the laws which regulate them made out, to those more abstruse inves- 
tigations on the laws of gravitation and those other difficult problems which are 
now being worked out. 
The progress of knowledge of another form of all pervading force, which we 
call from its most notable effect on one of the senses, light, has not been less 
remarkable than that of gravitation. 
Galileos discovery of the satellites of Jupiter supplied Romer with the data 
for measuring the velocity of light. Descartes, in his theory of the Rainbow, 
referred the different colours to the different amount of refraction, and made 
a near approximation to Newton's discovery of the colours entering into the 
composition of the luminous ray, and of their different rcfrangibilitj^. Hook, 
and llughens, and Newton, entered into explanations of the phenomena of light, 
and the names of Young, Malus, Fresnell, Arago, Brewster, Stokes, Jarmin, 
and others, have been successively associated with the disco veries of achromatism, 
of the laws of double refraction, of polarization, circular and elliptical, of dipola- 
rization, and those later advances of optics which have realized more than Bacon 
conceived might flow from the labours of his " perspective house." Some of the 
rational sciences, as wc now comprehend them, had not germinated in Bacon's 
time. Chemistry was then alchemy ; Geology and Paleontology were undreamt 
of ; but magnetism and electricity had begun to be observed and their phenomena 
compared and defined, and entitled to be regarded as the first step toward a scien- 
tific knowledge of those powers. 
It is true that long before the 17th century the magnet was known, and the 
compass had guided the mariner's bark through trackless seas, but to Gilbert is 
due the observation of the phenomena that electricity attracted light bodies, 'while 
magnetic force acted upon iron only. 
A century later the phenomenon of repulsion was detected. The conduction of 
electric force and the different buhavio'ir of bodies in contact leading to their 
division into conductor and non-conductor next followed. The definition of two 
kinds of electricity, negative and positive, formed an important step, which led to 
a brilliant series of experiments and discoveries, with inventions, such as the 
Leyden jar for intensifying the electric shock. The instantaneous transmission 
bi electric force, the application of the lightning conductor, the association, as be- 
