One word of counsel to planters on soil tending to dryness--never plant oak forest pure, but let beech be mixed with the oaks. The importance of this is well known to German foresters, who call beech the doctor of the forest. Its dense foliage prevents undue evaporation under parching winds and scorching sun, and its heavy leaf-fall in autumn creates the best kind of forest soil. No clearer example can be given of the failure of ancient oaks, not from extreme age, but from the parching of the soil, than is presented in Sherwood Forest. The giant trunks that stand there singly or in scattered groups once supported a far loftier dome of foliage than they do now. The branches have died back through the vigour of the tree being sapped by excessive evaporation from the ground, consequent on the loss of forest canopy and undergrowth. Within Lord Manvers's park of Thoresby, formed long ago by enclosing part of the Forest, oaks of the same age as those outside stand in close company with the fostering beech, and clothed with dense foliage to the very end of the branches. How often has one heard a forester, when a great oak goes "stag-headed," explain this as the result of the roots getting down to unsuitable subsoil; whereas the true reason is that an oak cannot fulfil his allotted span of years except when grown in close company of other trees. As might be expected, the oak, as monarch of the primæval British forest, has contributed names to countless places, both in Celtic and Saxon speech; besides a few in Norman French, whereof Chenies, a parish in Bucks, may serve as an example. The Saxon _ac_, still current in the north, but supplanted in the south by the broader "oak," is easily detected in such names as Acton, Aikton, Ackworth, Akenham, in England; Aikrig, Aikenhead (sometimes disguised by an intrusive _t_ as Aitkenhead) and Aiket, which is a contraction of the Saxon _ac widu_, oak-wood. Oakham, Oakford, Oakenshaw, Oakley, etc., speak for themselves. In old Gaelic the oak was _daur_, in modern Gaelic the genitive _dara_ or _darach_ is used, but in Manx and Welsh it remains _dar_. Deer, Darroch and Darra are Scottish place-names retaining respectively the old and new form of the word, the latter often appearing in composition, as in Kildarroch, i.e. _coill darach_, oak-wood. Still commoner is the derivative _doire_, originally _daire_ (pronounced "derry"), signifying primarily an oak-wood, but later applied to woods in general. Hence the large class of names like Derry, Dirriemore, Derrynabrock, Derrynahinch, etc. St. Columba founded his monastery at a place called Daire-Calgaich in the year 546. Adamnan, writing a hundred years or so later, glossed this name _Roboretum Calgachi_, Calgach's oak-wood. After this it became Derry-Columkille, the oak-wood of Colum of the Churches, until finally James VI. and I. granted a charter thereof to a London company of traders, and the place became, and remains, known as Londonderry.