noxious to the corn, and as a vehicle to convey it in the direction 

 of the rays, (which necessarily is that of the shade.) As the injury 

 is done in the line in which the direct rays of light pass through 

 the tree, it must follow that neither air nor water are solvents of 

 this body, for if they were, it would be wafted in different direc- 

 tions, if this idea is just, what a field does it open for important 



In 1793, Chancellor Livingston made another communication, 

 detailing his observations on the effects of light passing through 

 chestnut, black oak, mulberry and apple trees, on a field o( buck- 



which I have made with attention, under the most favorable cir- 

 cumstances, as well with respect to the position of the trees, the 

 nature of the vegetable, and the season of the year, has confirmed 



tables receive from the shade ofccrtain trc,es,!is not owing simply to 

 the diminution of light, but either to a change the light undergoes 

 in passing through them, or from its dissolving and becoming the 

 vehicle of some substance noxious to certain plants, contained in 

 the tree through which it passes. There are few facts in physics 

 that do not admit of useful deductions. I have taken pains to es- 

 tablish this, that you or some other chemist of more leisure and 



For the purpose of my theory I will now take it for granted that 

 the observations of Chancellor Livingston satisfactorily prove that 



certain substances, and after such decomposition, can and do, car- 

 ry with them parts of such substances and impart them to remote 

 objects. Or that, in some other manner, properties inherent in 

 the leaves of trees, are by the sun-beams conveyed to distant ob- 

 jects. The luminous girdle round the moon (if I may so call it) 

 what was it or what was the cause of its appearance « There 

 must have been something occupying that space, with properties, 

 either to radiate light or to reflect it, or, when the sun was behind 

 the moon, to refract a portion of his rays so as to fall in parallel 

 lines on the eye. In support of the two first suppositions no facts 

 or reasons are known, sufficient to raise a plausible presumption. 

 The last supposition is therefore that which I shall adopt ; and for 

 its support it requires only the admission that the moon has a trans- 

 parent atmosphere to the extent of this luminous girdle. 



