288 Effects of Terrestrial Radiation 



remain unknown ; the pursuit is a species of rude chance 

 game : not to mention the world of life and interest which a 

 correct knowledge of the chemistry of vegetation can impart 

 to the cultivated intellect. The physiology of plants, or the 

 laws and phenomena of vegetation, forms one of the most 

 interesting and beautiful domains of chemical science. In 

 saying thus much, however, I would not be understood as 

 underrating the importance of meteorological phenomena, 

 which rule the atmosphere in its temperature, barometry, 

 and hygrometry. These are essentially connected with the 

 rise, progress, and decay of vegetation, or its full establish- 

 ment in the attitude of healthy luxuriance. Above all (though 

 a question too lightly esteemed) is the electrical condition of 

 the atmosphere, and the electrical relations of individuals which 

 constitute the living mass of vegetation. It is to be regretted 

 that the practical gardener discards every instrument save 

 the thermometer. Although I am far from denying it a place, 

 and that an important one, in the scale of usefulness, I 

 mean to assert that the hygrometer and aerial electroscope 

 may safely dispute with the thermometer the point of priority. 

 At the present time, however, it would be premature in me 

 to allude to a series of experiments now in progress, and 

 which promise curious and interesting results. I may safely, 

 however, venture to say that the laws and phenomena of 

 radiation, too little attended to in even the science of horti- 

 culture, are in many instances the very hinges on which the 

 success of an abundant and mature crop of fruit depends. 



In the present communication, with your permission, I shall 

 supply a few remarks connected with the cultivation of the 

 vine in this country (in the open air), as elucidating scien- 

 tific principles which I am engaged in carrying into effect, 

 as I am anxious to bring the question before your readers 

 as early as possible, to enable them, should they approve 

 of my reasoning and plan of pursuit, to follow out into 

 practice the principles now propounded for their consider- 

 ation. To this I shall add a few observations on the 

 Chinese method of propagating fruit trees ; and I may avail 

 myself of a future opportunity to transmit a model of an 

 improvement I have inade in the machine employed to enclose 

 the ball of earth and confine the newly formed roots. 



It has been shown that the cooling process of radiation, by 

 which the temperature of the surface of the earth is lowered 

 so considerably, differs materially on the inclination of the 

 hill compared with the bosom of the valley. Mr. Daniell, 

 indeed, states, on one occasion, a difference amounting to 30° : 

 that is to say, the thermometer on the inclined surface main- 



