384< Instrument for talcing the HeigJits of Tr<:cs. 



trenched too deep; nor indeed can any soil, unless the subsoil 

 contains something noxious to vegetation. 



Pulverisation ought to go on during the process of vegetation, 

 by the free use of the fork or hoe. In summer such operations 

 prevent the soil getting dried up, as evaporation proceeds more 

 rapidly from a hard surface than a loose one. It is some time 

 before water can penetrate a hard surface, upon a loose one it 

 sinks to the roots at once- The more soil is stirred among crops 

 of any description, the more fibres will plants produce, and this 

 increase of strength to the plants will more than pay the labour. 

 Independent of the neat and orderly appearance of the drill 

 system among culinary vegetables, it possesses the advantage of 

 enabling us freely to stir the soil : for this purpose I consider a 

 three-pronged fork preferable to a hoe, as by using the latter the 

 ground gets hard below. Believing pulverisation to be of great 

 importance for loosening the texture of strong soils, enabling the 

 fibres of plants to run in all directions in search of food, imbib- 

 ing and imparting a sufficiency of moisture, without receiving 

 too much, or retaining it too long, and also as tending to eradi- 

 cate deleterious properties in the soil, I should wish to see it 

 more generally adopted, and extended to the cultivation of many 

 of our field crops. 



Exotic Nursery, King's Hoad, May 18. 1840. 



Art. V. Description of an Instrument used for taking the Heights of 

 Trees. By H. W. Jukes, Esq. 



In the autumn of 1836 I spent several months at Studley 

 Royal, in Yorkshire, the residence of Miss Lawrence, making 

 portraits of trees for the Arboretum Britaniciim. As these por- 

 traits were all drawn to a scale, it became necessary to measure 

 the trees ; and their heights were taken with the instrument or 

 machine of which fg. 47. is an outline, to a scale of a foot 



to an inch. This instrument consists of a thin board of oak, 

 2 ft. 9 in. long, shaped like a gun-stock, the end a being adapted 

 for the shoulder, the muzzle or line b c for taking a sight of 

 the top of the tree, and the square, of which c d\s o, side, being 

 marked or cut on the board at the farther extremity. The 



