TREES IN TOWNS 55 
providing shelter, but they cannot be utilised in streets. 
The curious Chinese maidenhair tree (Ginkgo biloba) thrives 
in London, and is worthy of a place in town parks and 
gardens on account of the remarkable beauty of its foliage. 
In the planting of streets it must be remembered that 
trees die unless their roots are freely supplied with air as 
well as moisture. Pavements, such as asphalt, which seal 
up the soil from access to the air, render the growth of 
trees impossible. The planting of trees, as is now usually 
done in English towns, with grilles or iron gratings around 
their bases, which are supposed to admit sufficient air and 
moisture to the roots, is a poor practice. Trees planted 
in this way never do well. Moreover, the gratings are 
expensive, and in all probability are not more effective 
for the admission of air and rain than ordinary gravel. 
The universal practice in America of planting trees along 
a continuous strip of grass turf should be adopted wherever 
possible. The width of the grass strip should be at least 
4 feet. The narrowest street which can be conveniently 
planted is 50 feet wide; and this may be divided into a 
30-feet roadway with two footpaths each 10 feet in width, 
the latter consisting of a 6-feet pavement next the houses 
and a 4-feet planting strip next the curb. A broad strip 
of turf between the walk and the curb enhances the beauty of 
the street, and gives the trees a better chance of vigorous life. 
Streets 60 feet wide are ideal, with a roadway 30 feet 
wide, and footpaths each 15 feet wide, on which can be laid 
out a lawn strip of 6 feet. In residential quarters, the 
houses are usually set well back, and at some distance from 
the footpaths, which gives more room for the trees to develop. 
In Paris no trees are planted on streets with tall buildings, 
which have footpaths less than 13 feet wide and roadways 
20 feet wide. Narrow pavements and sharp corners of 
streets are unsuitable for trees. Trees should be set about 40 
feet apart in the line, alternately in the two rows in a street. 
Free-growing, clean, healthy young trees with good roots 
must be chosen; and the best size is about 2 to 3 inches 
in diameter. The single stake is best, such as a larch pole, 
