GKOWTH OF WOOD IN DECIDUOUS AND EVERGREEN TREES. 



63 



the same injury as those of the former ; but in the years now under considera- 

 tion I cannot trace any such effect. 



In a climate such as ours, with frequent variations from the average in the 

 monthly rainfall, considerable effects on the growth of wood may be expected 

 from excess or deficiency of rain at the growing season. To trace these effects 

 may be difficult, from the possible simultaneous action of other causes immediate 

 or remote ; nevertheless I think something may be made of an examination of 

 the principal abnormalities in the rainfall during the three years in which 

 monthly observations of growth were taken. I owe to the kindness of Mr 

 Buchan the following Table, showing the excess or deficiency of rain during the 

 months of the period in question. The means from which these are calculated 

 are derived from twenty-eight years' observations at Charlotte Square, whereas 

 the monthly rainfall is taken from observations at Cumin Place, Grange ; but 

 the general results are not likely to be seriously affected by this difference. 



Table X. — Monthly Excess or Defect of Rain at Edinburgh in 1880, 1881, and 1882. 





Jan. 



Feb. 



March. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



1880, . 



1881, . 



1882, . 



-1-69 



-0-70 

 -0-55 



+ 0-03 

 + 2-81 

 + 0-01 



-0-09 

 + 0-13 

 + 1-04 



+ 0-11 

 -0-32 

 + 1-00 



-1-05 



-0-04 

 + 0-29 



-0-46 

 -0-61 

 + 0-28 



+ 1-91 

 + 0-52 

 -0-51 



-2-46 

 + 3-06 

 -0-85 



+ 0-17 

 + 0-97 



+ 1-66 

 -0-50 



+ 1-54 

 + 0-60 



+ 1-01 

 -0-83 



In comparing the rainfall with the tree-growth, I shall make use of the 

 proportion which the monthly percentage of the latter bears to the whole annual 

 growth. These will be found in Table VI. and VII. 



1880. — The rainfall of May was less than half the average, and that of June 

 was deficient by about a third ; but the increase of wood in both classes of trees 

 was quite up to the average of the same period for three years. In July the 

 rainfall was much in excess : the deciduous growth was an average one ; but 

 the evergreen growth was much above the average. In August there was a 

 great deficiency of rain, — 2"46, and an excess of heat, + 3°*3 ; the deciduous 

 growth was about an average, the evergreen greatly below average. 



1881. — In April, May, and June there was a deficiency of rain, but it only 

 amounted to an inch in all, and as vegetation was completely checked by severe 

 weather till the middle of April, the small proportionate growth of both classes 

 of trees in May and June may fairly be attributed to the latter cause. In July 

 the rainfall was slightly in excess : the deciduous growth was again an average, 

 but the evergreen under average. In August, the memorable month of the 

 Volunteer Review at Holyrood Park, no less than 6 inches of rain, double the 



