Hot in Larch. 545 



it extended to 4 decimal parts of an inch. In 1819, during the 

 vegetating season (that season commencing at the beginning of 

 April, and terminating at the end of October), 16 in. of rain fell 

 at this place. I mention this circumstance, because it is well 

 known that a scanty or a liberal supply of moisture during the 

 growing season is invariably followed, in healthy-growing larch 

 trees, by a corresponding deposit in width. This year, the 

 annular layer of wood measured *5, or half an inch. The ave- 

 rage fall of rain, during the vegetating season in 1820, 1821, and 



1822, was 13 in. in each year; and the average annual deposit 

 of wood for each of these years is "22 of an inch. In the year 



1823, the rain that fell in the summer months amounted to 

 21 in. ; the temperature was low throughout this season, and the 

 crops were unusually late in being secured. The annular layer 

 of wood in this year measures half an inch. In the years 1824 

 and 1825, the rain for the same period measured 13 in. in each 

 year ; and, in each of these years, the layer of wood measured 

 3 decimal parts of an inch. In 1826, the quantity of rain in the 

 summer months was, it will be easily remembered, unusually 

 small ; only 7 in. fell during the vegetating season, and about 

 other 7 in. in what are termed the dead months of the year. 

 The annular layer of wood for this year only measures *2 of an 

 inch. 



During the vegetating season of four following years, the fall 

 of rain averaged 18^ in. annually; and the annual deposits for 

 each of these years averaged *37 of an inch. Hitherto all seems 

 to have gone on well; and, up to 1830, the tree seems to have 

 been in a healthy state : but, although the rains were moderate 

 in 1831, 1832, and 1833, the annual deposit for each of these 

 years measures only 14 decimal parts of an inch ; giving reason 

 to suppose that the tree had become infected with the disease in 

 1830. The rot appears to have commenced on the south and 

 east sides of the tree, and to have spread irregularly in that 

 direction between the annular layers of 1823 and 1832. I must 

 here beg to call Mr. Munro's attention to the facts, that the 

 central layers are all sound up to 1823 ; and, as far as this spe- 

 cimen is concerned, " an extensive annual deposit of alburnum 

 has" no " hand in the matter (IX. 555.), and that the growth 

 of the first ten years has " not " given way." I have been the 

 more particular in my description of this tree, it being the only 

 one in thirty, of the same age, in which the least symptom of 

 disease has appeared. The larch trees in this spot, now cut, 

 stood from 20 ft. to 30 ft. apart, among oaks, with an under- 

 growth of filberts ; and, being in a conspicuous situation, I had 

 encouraged most of the trees to assume a natural shape by per- 

 mitting the lower branches to remain extended at full length 

 down to the ground. The trees, in spring and summer, assumed 



a q 3 



