42 IN STARRY REALMS. 



and be utilised when occasion might require. There is in 

 fact only one weak point in the scheme of the Lagado pro- 

 fessor : its economical aspect is unsatisfactory. The heat 

 of the sunbeams could only be recovered from cucumbers 

 at an utterly prohibitive cost. Nevertheless, the heat is 

 there, and in plants of other growths it becomes quite 

 possible not only to extract the latent sunbeams, but even 

 to do so with the highest profit and advantage. Sunbeams 

 may shine on a tree for a few decades, the leaves may each 

 summer garner the sunbeams which fall on them and 

 incorporate those sunbeams in the solid trunk of the tree. 

 In due time the tree is felled, logs of it are thrown on the 

 fire, and pleasant light and warmth radiate from the 

 hearth. It is not a mere flight of poetical fancy to regard 

 the light and heat from a fireplace as the sunbeams re- 

 transformed to the active state from a condition of inert- 

 ness. It is an undoubted scientific truth. 



Let us ponder on the character of the process by which 

 the leaves of a plant contribute so largely to the building 

 up of its solid stem. Wood consists chiefly of the element 

 carbon in association with small quantities of mineral ingre- 

 dients. The growing tree draws its supplies of the neces- 

 sary material partly from the earth and partly from the 

 air. The earth provides, speaking generally, the mineral 

 jonstituents ; but carbon, which is the essential charac- 

 teristic of wood, and which is the principal source of the 

 heat- giving qualities of a log fire, is chiefly obtained from 

 the air. 



The atmosphere contains a certain proportion of car- 

 bonic acid gas, which is composed of the element carbon 

 in combination with oxygen. To understand what takes 



