number of rings, according to an ascertained standard rate of increase, still awaits the coming of a better system to supersede it. The obtruding difficulty which now meets us is, Where are we to measure the girth? Sir Robert Christison thought the ground level best, but, wherever possible, he also measured the tree at five feet from the base[961]. Yews, however, frequently thicken upwards; there may be swellings under the branches; the stem is often encumbered by bunches of young sprays; aged trees are usually deformed, and are studded with knobs and excrescences. To follow Christison’s plan with the trees at Dryburgh, Roseneath, and Sanderstead, and other yews which have protuberances at the base, would result in too liberal an estimate. The reaction of root-pressure tends to make trees “lift themselves out of the ground.” Moreover, in exposed situations, scraping animals, such as rabbits and foxes, lay bare the roots of trees, and increase the apparent girth. Rain tends to wash away the soil, and so aids in the deception. On the other hand, the level of the soil in churchyards is gradually rising (cf. p. 90 _supra_), and it is primarily with churchyard yews that we are concerned. Hence it is proposed that the measurement should be taken at the base, and also at a height of three feet from the ground. De Candolle recommended a height of two feet for exogenous trees. Those who have had practical experience in measuring yews, will, while employing the tape at both these levels, recognize that there must be a slightly varied treatment for each individual tree. Perhaps, like Sir R. Christison[962], the investigator will be impelled, where the trunk is short, to take the girth at the narrowest part. Unfortunately few actual records have been kept of measurements of yew trees taken at intervals. One or two cases may, however, be instructive. At Hurstbourne Tarrant, near Andover (Hants), there are two churchyard yews, which, the parish register informs us, were planted in 1693 and 1743 respectively. Now, if we accept Dr Lowe’s mean rate of one foot for 65 years, the first tree, when re-measured in 1896, should have been about 9´ 10´´ in circumference, and the second 7´ 6´´. The actual measurements were[963]: 1st tree. 8´ 4´´ at base; 6´ 8´´ at a height of five feet. 2nd “ 7´ 3´´ “ “ ; 7´ 3´´ “ “ “ “ Hence Dr Lowe’s rate of growth would be too high for these trees; in the first example, markedly, yet the trees were still only of moderate age, and growth must have been active. Other good records refer to two yews in the churchyard of Basildon, Berkshire. Details of the measurement of the first tree were entered in the parish register in 1780, and of the second in 1834, though both trees had been planted by Lord Fane at a considerably earlier date than the year 1780. In 1889 the trees were again measured by Mr Walter Money, and the results thus compared[964]: