The Canadian Horticulturist. 365 



. Such drives are usually constructed with a foundation of stone spalls on 

 coarse gravel and surfaced with finer gravel or finely crushed stone. The cases 

 are rare where a substantial macadam structure is built, but the principles 

 governing the macadam process should be followed as closely as circumstances 

 will permit. These may be briefly stated as a guide to the inexperienced. 



The depth of structure should be sufficient when firmly compacted to 

 support without yielding the heaviest loads likely to pass over it and to with- 

 stand displacements by frost. This will depend largely upon the nature of the 

 subsoil and the drainage conditions in wet weather. The common depth for 

 local drives varies from six to twelve inches, but there may be conditions where 

 a depth of 18 inches is necessary. It may be naturally supposed that a depth 

 of 18 inches is only three times as strong as a depth of 6 inches, but in reality 

 it is nine times as strong. The pressure of a load spreads through the roadway 

 in the form of a cone with its apex at the wheel. The area of the base of this 

 cone increases as '' the square of the depth." Thus if the depth of " macadam ' 

 be 6 inches, the weight at the bottom will be spread over 36 square inches. A 

 depth of 12 inches will be four times as strong, and the bearing surface as the 

 bottom will then be 144 square inches and so on. 



When the structure is given a depth of 1 2 to 18 inches, the bottom half is 

 usually built up with rough stones and spalls compactly placed, and the inter- 

 stices filled with small stones. Over this to the surface grade is placed one 

 or more layers of stone broken into angular cubes of one to two inches across. 

 This is thoroughly rammed or rolled into place, and then covered with a thin 

 layer of fine gravel, or fine screenings from a steam stone crusher. Where 

 work of this kind is now done on a large scale, the macadam stone is all 

 broken by machinery, and the material is thoroughly compressed by a steam 

 road roller of 18 to 20 tons weight. Sprinkling carts are also used in further 

 compacting the surface layer, and thus a smooth and hard driveway is at once 

 secured. — Wm. McMillan, in Gardening. 



The Myrtle. — Another " classic " is the Myrtle, Myrtus communis. It 

 grows to be a large, compact, shrubby plant, thickly set with shapely branches, 

 and, when well grown, these branches are covered with small, white flowers, 

 having a rich fragrance. The leaves are evergreen and shining, and, when brushed 

 or bruised, they also are fragrant. It must have plenty of pot room, delights in 

 being bedded out in summer, and a rich soil, such as you would give Roses and 

 Carnations. Three things must be closely guarded against in growing the 

 Myrtle, hot sunshine, sour soil from imperfect drainage, and the red spider. 

 Sprinkle the leaves daily, shift into larger pots occasionally, and do not give too 

 high a temperature. For bouquet work it is very valuable, and grown into a 

 large, handsome shrub it is ornamental in a high degree. Cuttings of the yOung 

 wood root easily. There is a double variety, also, which is said to be very 

 beautiful, but I have never seen it. — Vick's Magazine. 



