CONSIDERATION OF LIGHT. 
59 
and made to revolve by means of another wheel worked by w T ater, in such a 
manner, that the number of the revolutions could be regulated ; the beans were 
supplied with moisture, and were placed under circumstances favourable to 
germination. The beans all grew, notwithstanding the violence of the revolution, 
which was sometimes as much as 250 revolutions a minute on the vertical wheel — ■ 
which always revolved rapidly — and with little variation of velocity ; the radicles, 
or roots, pointed precisely in the direction of radii in whatever direction they w T ere 
placed. The germs took precisely the opposite direction, and pointed to the 
centre of the wheel, where they soon met each other. Upon the horizontal wheel 
the conflicting operation of gravitation and centrifugal force, occasioned the germs 
to form a cone more or less obtuse, according to the velocity of the wheel, the 
radicles always taking a course diametrically opposite to that taken by the germs, 
and, consequently, pointing as much below as the germs pointed above the plane 
of the wheel's motion/ 1 
Mr. Knight, by this ingenious experiment, failed to prove the agency of 
gravitation, for, to say nothing of the effects of mere mechanical force upon the 
germinating beans, by a velocity so great, he overlooked the presence of excited 
electricity. The attempt, at best, was very artificial, and would tend to no natural 
conclusions ; but as to gravitation in the abstract, what is it ? and what does the 
term express ? A body gravitates, when it falls to the earth ; but when we 
consider that the earth is a globe, and that all bodies above its surface fall towards 
that surface, and therefore at every angle converging towards a central point 
which the globular figure admits of, it becomes plain that the act which we call 
descent, or falling, must be produced by attraction ; and thus we are inevitably led 
to the exciting cause, the light of the sun> which by its beams electrifies or 
magnetizes all the revolving worlds belonging to its system, and renders them 
mutually co-attractive. 
Tims, also, we interpret the phenomena of vegetable developments, as the direct 
solar light appears to effect the induction of those electrical currents which 
regulate the flow of the sap, the laboration of the proper juice and compound 
secretions, and the separation and fixation of the colouring principle. 
Colour is the ornamental dress of the vegetable kingdom. — Whence is it 
derived — what its source ? We know that in the dark some plants acquire rich 
and deep tints : thus, the red giant Rhubarb, if placed in a warmish, close cellar, 
developes leaves, the stalks being of a most brilliant crimson, while the plate is of 
a rich lemon- colour. In the light, growing naturally, the stalk would be a dark 
ochreous red, and the leaf-plate a full green. Light therefore, influences, by 
inducing chemical action in peculiar juices. 
The solar ray is decomposable into four defined colours, and into three degrees 
of blue. By combination, these tints may be rendered productive of every shade 
of colour. It becomes, therefore, an inquiry of lively interest whether each ray 
fixes or deposits its own simple tints, or whether it acts electro-chemically upon 
