270 



Philadelphia Agricultural Society — lis Premiums. 



Vol. X. 



and, consequently, pointing as much below 

 as the germs pointed above the plane of the 

 wheel's motion." 



Mr. Knight, by this ingenious experiment, 

 failed to prove the agency of gravitation, for, 

 to say nothing of the effects of mere me- 

 chanical force upon the germinating beans, 

 by a velocity so great, he overlooked the 

 presence of excited electricity. The at- 

 tempt, 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 1 A body gra- 

 vitates 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 re- 

 volving worlds belonging to its system, and 

 renders them mutually co-attractive. 



Thus, also, we interpret the phenomena 

 of vegetable developements, as the direct 

 solar light appears to efl^ect 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 ve- 

 getable 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, influ- 

 ences, by inducing chemical action in pecu- 

 liar 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 elec- 

 tro-chemically upon certain fluids, which are 

 destined to be the colouring media. In the 

 absence of proof, we may still appeal to a 

 few facts adduced by several authorities. 



Influence upon leaves — developing Chlo- 

 rophyll. — It frequently happens in America 

 that clouds and rain obscure the atmosphere 

 for several days together, and that, during 



this time, buds of entire forests expand 

 themselves into leaves. "These leaves as- 

 sume a pallid hue till the sun appears, when, 

 within the short period of six hours of a 

 clear sky and bright sun, their colour is 

 changed to a beautiful green." 



In Silliman's Journal a circumstance of 

 this kind is recorded, whereby it appears 

 that in six hours the tinting of several miles 

 of a forest went through all the grades, from 

 that of a greenish- white to full spring ver- 

 dure. 



Every gardener is conversant with the va- 

 riations of colour which flowers assume un- 

 der artificial treatment: thus, Andromeda 

 polifolia, and Kalmia latifolia, are purple 

 or pink when growing in the open air, but 

 become nearly white when made to flower 

 under glass. Now, it is not the heat alto- 

 gether that influences the flower, but light, 

 modified by passing through glass. Hence, 

 we should study the effects of all those de- 

 grees of heat in which any tender or half- 

 hardy plant can thrive, and adapt them to 

 the actual volume of clear sunlight, because 

 a heated atmosphere is not a substitute, — or, 

 at least, a very defective one — for the clear 

 ray, inasmuch as it (heat) produces no chem- 

 ical effect upon the fluids of either leaf or 

 flower. 



Light acts beneficially upon the upper 

 surface of the leaves, and hence great cau- 

 tion is indicated in allowing space sufficient 

 for full play and action ; it also promotes 

 the transpiration of superfluous moisture and 

 gases ; and these appear to transude chiefly 

 through the stomates of the under surfaces. 



We begin to acquire fresh evidence of 

 electric action in the new experiments upon 

 corn-growing when exposed to the agency 

 of electric circuits. All nature, air, water, 

 earth, are replete with masked light, and 

 this can be derived only from the sun ; if 

 then it become a well established fact,"' that 

 the growth of plants can be doubly stimu- 

 lated by electricity derived from the atmos- 

 phere, we establish that most important 

 point — the electrizing principle of the sun's 

 rays. In a few months we hope to collect, 

 and be enabled to adduce, facts in proof of 

 the theory thus cursorily hinted at. 



For the Farmers' Cabinet. 



Philadelphia Agricultural Society— Its 

 Premiums. 



Your correspondent, I. U., in j'our last 

 No., who doubtless means to give wholesome 

 advice to the Philadelphia Agricultural So- 

 ciet}', has ventured some assertions and 

 statements which should not pass unnoticed. 

 He is not singular in the opinion that the 



