Mr Monteath states that Scots fir should not be thinned to greater distance than 20 feet apart, and larch 15 feet. This shews very little consideration: the distance apart necessary for these kinds of timber, and of all other kinds, must be relative to the soil, situation and climate, and the intentions of the owner, whether he means to bring them soon to {152} market, or carry them forward to great timber. When fir trees are intended to be early cut down, or when disease in larch from unfitness of soil may be apprehended, as it is thence of small consequence though their future ability to become great timber be destroyed by closeness, the plants should be retained pretty near each other from the first, that the timber may be tall, straight, and clean. On the other hand, when the soil is suitable and great timber intended, early attention to thinning and great openness from the first is absolutely necessary, as they (the firs), different from other trees, can never repair the loss of their lower branches by throwing out new ones from the naked stem; and double the distance stated by Mr Monteath at least for larch, which, instead of less, needs more space than Scots fir, will be required. We believe the decay of Scots fir, occurring so generally at about 40 years of age, although also dependent on inferior variety and kiln-drying of cones, arises principally from want of timely thinning; that is, that the infirm variety of Scots fir in common use, when supported by numerous feeders, and not weakened by being drawn up into a tall slender stem, will often have hardihood to continue growing, and acquire considerable size in our cold, wet, moorish tills, or even in our moorish {153} sandy flats. Many casualties will, however, occur among resinous trees[37], especially in unsuitable soil, even when the plants rise from the seed naturally sown, and have sufficient room for lateral expansion. The same cause, viz. closeness or want of thinning, induces early maturity, old age and decay in larch, although it does not seem to have any influence, either as inducement to, or prevention of, the rot. We have heard men,—even men reasonable on other subjects—speak of allowing a pine wood to thin itself: as well might a farmer speak of allowing his turnip field to thin itself. When woods are planted of various kinds of timber, the stronger, larger growing kinds will sometimes acquire room by overwhelming the smaller: but when the forest is of one kind of tree, and too close, all suffer nearly alike, and follow each other fast in decay, as their various strength of constitution gives way; unless, from some negligence or defect in planting, a portion of the plants have come away quickly, and the others hung back sickly for several years, so that {154} the former might master the latter: or when some strong growing variety overtops its congeners. In the natural forest of America, when a clearance by any means is effected,