August 12,1S71.3 THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
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University of Oxford has already established a physical 
laboratory. The munificence of its Chancellor is about 
to supply the University of Cambridge with a splendid 
laboratory, to be constructed under the eye of Professor 
Clerk Maxwell. 
Besides abstracts of papers read and discussions held 
before the sections, the annual Reports of the British 
Association contain a large mass of valuable matter of 
another class. The speaker then alluded to the early 
practice of the Association, a practice that might well 
be further developed, to call occasionally for a special 
report on some particular branch of science from a man 
eminently qualified for the task. Some of the reports 
received in compliance with these invitations have done 
good service in their time, and remain permanently 
useful as landmarks in the history of science. The two 
kinds of efficiency realized in this department of the 
Association’s work may be illustrated by referring to 
Cayley’s Report on Abstract Dynamics and Sabine’s 
Report on Terrestrial Magnetism (1838). 
He then referred to different investigators of the 
science of terrestrial magnetism, and said that in Wales, 
Sir Edward and Lady Sabine arc at work on the mag¬ 
netic chart of the world. If two years of life and health 
arc granted to them, science will bo provided with a key 
which must powerfully conduce to the ultimate opening 
up of one of the most refractory enigmas of cosmical 
physics, the cause of terrestrial magnetism. 
In giving a sketch of scientific investigation performed 
during the past year he would simply choose some of 
those which had struck him as most notable. 
Accurate and minute measurement seems to the non- 
scientific imagination a less lofty and dignified work than 
looking for something new. But nearly all the grandest 
discoveries of science have been but the rewards of accu¬ 
rate measurement and patient and long-continued labour 
in the minute sifting of numerical results. The popular 
idea of Newton’s grandest discovery is that the theory 
of gravitation flashed into his mind, and so the discovery 
was made. It was by long train of mathematical calcu¬ 
lation, founded on results accumulated through prodi¬ 
gious toil of practical astronomers, that Newton first de¬ 
monstrated the forces urging the planets towards the sun, 
determined the magnitudes of those forces, and discovered 
that a force following the same law of variation with 
distance urges the moon towards the earth. Then first, 
we may suppose, came to him the idea of the universa¬ 
lity of gravitation; but when he attempted to compare 
the magnitude of the force on the moon with the magni- j 
tude of the force of gravitation of a heavy body of equal 
mass at the earth’s surface, he did not find the agree¬ 
ment which the law he was discovering required. Not 
for years after would ho publish his discovery as made. 
It is recounted that, being present at a meeting of the 
Royal Society, he heard a paper read, describing geodesic 
measurement by Picard which led to a serious correction 
of the previously accepted estimate of the earth’s radius. 
This was what Newton required. He went home with the 
result and commenced his calculations, but felt so much , 
agitated that lie handed over the arithmetical work to a 
friend: then (and not when, sitting in a garden, he saw 
an apple fall) did he ascertain that gravitation keeps the 
moon in her orbit. 
Other instances of important results from minute and 
accurate measurement were mentioned, and an opinion 
expressed that great service has been done to science 
by the British Association in promoting accurate mea¬ 
surement in various subjects. 
The greatest achievement yet made in molecular 
theory of the properties of matter is the Kinetic theory 
of Gases, shadowed forth by Lucretius, definitely stated : 
by Daniel Bernoulli, largely developed by Herapath, 
made a reality by Joule, and worked out to its present 
advanced state by Clausius and Maxwell. Joule, from his 
dynamical equivalent of heat, and his experiments upon 
the heat produced by the condensation of gas, was able 
to estimate the average velocity of the ultimate mole- 
cules or atoms composing it. His estimate for hydrogen 
was 6225 feet per second at temperature 60° Fahr., and 
6055 feet per second at the freezing-point. Clausius 
took fully into account the impacts of molecules on one 
another, and the kinetic energy of relative motions of 
the matter constituting an individual atom. He investi¬ 
gated the relation bet ween their diameters, the number 
in a given space, and the mean length of path from 
impact to impact, and so gave the foundation for esti¬ 
mates of the absolute dimensions of atoms, to which I 
shall refer later. Ho explained the slowness of gaseous 
diffusion by the mutual impacts of the atoms, and laid a 
secure foundation for a complete theory of the diffusion 
j of fluids, previously a most refractory enigma. The 
deeply penetrating genius of Maxwell brought in visco¬ 
sity and thermal conductivity, and thus completed the 
dynamical explanation of all the known properties of 
gases, except their electric resistance and brittleness to 
electric force. 
No such comprehensive molecular theory had ever 
been even imagined before the nineteenth century. De¬ 
finite and complete in its area as it is, it is but a well- 
drawn part of a great chart, in which all physical 
science will be represented with every property of matter- 
shown in dynamic?.! relation to the whole. The prospect 
we now have of an early completion of this chart is 
based on the assumption of atoms. But there can be no 
permanent satisfaction to the mind in explaining heat, 
, light, elasticity, diffusion, electricity and magnetism, in 
| gases, liquids, and solids, and describing precisely the 
| relations of these different states of matter to one another 
by statistics of great numbers of atoms, when the pro— 
perties of the atom itself are simply assumed. "When the 
theory, of which we have the first instalment in Clausius 
and Maxwell’s work, is complete, we are but brought 
face to face with a superlatively grand question, what is 
the inner mechanism of the atom ? 
In the answer to this question we must find the expla¬ 
nation not only of the atomic elasticity, by which the 
atom is a chronomotric vibrator according to Stokes’s dis¬ 
covery, but of chemical affinity and of the differences of' 
quality of different chemical elements, at present a mere 
mystery in science. Helmholtz’s exquisite theory of' 
vortex-motion in an incompressible frictionless liquid has 
been suggested as a finger-post, pointing a way which 
may possibly lead to a full understanding of the pro¬ 
perties of atoms, carrying out the grand conception of 
Lucretius, who “ admits no subtle ethers, no variety of 
elements with fiery, or watery, or light, or heavy prin¬ 
ciples ; nor supposes light to be one thing, fire another, 
electricity a fluid, magnetism a vital principle, but treats • 
all phenomena as mere properties or accidents of simple 
matter.” This statement I take from an admirable 
paper on the atomic theory of Lucretius, which appeared 
in the North British Review for March, 1868, containing 
a most instructive summary of ancient and modern doc¬ 
trine regarding atoms. Allow me to read from that 
article one other short passage finely describing the pre¬ 
sent aspect of atomic theory:—“The existence of the 
chemical atom, already quite a complex little world, 
seems very probable: and the description of the Lucre— 
tian atom is wonderfully applicable to it. We are not 
wholly without hope that the real weight of each atom 
may some day be known—not merely the relative weight 
of the several atoms, but the number in a given volume^ 
of any material; that the form and motion of the parts 
of each atom and the distances by which they are sepa- - 
rated may be calculated; that the motions by which 
they produce heat, electricity, and light may be illus- - 
trated by exact geometrical diagrams ; and that the fun- - 
damental properties of the intermediate and possibly 
constituent medium may bo arrived at. Then the mo¬ 
tion of planets and music of the spheres will be neglected 
for a while in admiration of the maze in which the tiny 
atoms run.” 
