NOTES AND QUERIES. 529 



holding soil, it has no rival; it will grow rapidly, and yield timber 

 of good quality; but on a light sandy soil signs of falling off have 

 been observed after the fortieth year. Its power to bear shade is 

 less than that of the spruce, for where the two species are growing in 

 contact, the lower branches of the Menzies die off earlier than those 

 of the spruce. It does not appear to be an abundant seed-bearer 

 in this country. It is certainly a tree which is well deserving of 

 further attention. 



Brief Statement of the Objects, Methods, and Results of 

 Measurements -of Girth-Increase in Trees undertaken 

 by the late Sir Robert Christison in 1878, and carried 

 on by Dr D. Christison to the present day. 1 



1. Objects. — Girth-measurement of trees, chiefly in the Botanic 

 Garden, Edinburgh, was initiated in 1878 by Sir Robert 

 Christison in order to establish an accurate system of measurement. 

 He showed that the measurements given in books of travels and 

 forestry were almost invariably useless from the neglect of the 

 simplest precautions, and pointed out the practical importance of 

 accuracy for estimating the cubic contents of trees, for ascertaining 

 when trees were ceasing to grow, and what were the effects of 

 position, pruning, thinning, etc. He laid down rules for taking 

 girth-measurements, and showed the erroneousness of De Candolle's 

 statement, until then not challenged, that after some years of 

 youth, trees increased nearly regularly for the rest of their lives. 

 Sir Robert afterwards directed his observations mainly to ascertain 

 the duration of the growing season, the annual rate of the different 

 species, and the effect of the hard winters 1879-80-81 in checking 

 girth-increase. 



Since my father's death in 1883 I have worked on the same 

 lines, but on a much larger scale and on younger trees, both to 

 compare with his older set and because they are more accurately 

 measurable. The great improvement in tapes, also, enabled me to 

 determine with greater accuracy the duration of the growing season 

 and the monthly rates, to undertake observations at fortnightly 

 and even at five-day intervals, and to ascertain the immediate effects 

 of low temperatures. Other new investigations were upon the 

 effects of pruning and transplanting. 



2. Methods. — My method is (1) to select smooth, cylindrical 

 stems as far as possible ; (2) to measure at 5 feet above ground, 



1 The detailed report has been printed for the Royal Botanic Garden, 

 Edinburgh. 



