J38 PHILOSOPHICAL TRANSACTIONS. [ANNO 1781. 



quently the muscles harder. The want of ventral fins induces me to believe, 

 that it is not a migratory species. It feeds on small crabs and fishes. 



XXIX. A Further Account of the Usefulness of Washing the Stems of Trees. 

 By Mr. Robert Marsham, of Stratton, F. R. S. p. 44Q. 



In the former account, Mr. M. showed how much a beech increased on it s 

 stem being cleaned and washed; and in this he shows that the benefit of clean- 

 ing the stem continues several years: for the beech which he washed in 1775 

 increased in the 5 years after the washing 8-^ inches, or above an inch and 

 T V yearly; and the aggregate of 9 unwashed beeches of the same age does not 

 amount to 1 inch and T v yearly to each tree. In 1776 Mr. M. washed another 

 beech of the same age, viz. seed in 1741; and the increase in 4 years after the 

 washing was Q-^- inches, or 2 inches and -^ yearly, when the aggregate of 9 

 unwashed beeches amounted to but 1 inch and T \ and a half. In 1770" he 

 washed an oak which he planted in 1720, which increased in the 4 years after 

 washing 7-^ inches, and the aggregate of 3 oaks planted the same year (viz. all 

 he measured) amounted to but 1 inch yearly to each tree. In 177Q Mr. M. 

 washed another beech of the same age, and the increase in 178O was 3 inches, 

 when the aggregate of 1 5 unwashed beeches was not full 1 5-^v inches, or not 1 

 inch and half a tenth to each tree; yet most of these trees grew on better land 

 than that which was washed. But Mr. M. apprehends the whole of the extraor- 

 dinary increase in the 2 last experiments should not be attributed to washing: 

 for in the autumn of 1778 he had greasy pond-mud spread round some favourite 

 trees, as far as he supposed their roots extended, and though some trees did not 

 show to have received any benefit from the mud, yet others did, that is, an oak 

 increased half an inch, and a beech -^, above their ordinary growth. Now 

 though the beech gained but -^, yet perhaps that may not be enough 

 to allow for the mud; for the summer of 1779 was the most ungenial 

 to the growth of trees of any since he had measured them, some not gaining 

 half their ordinary growth, and the aggregate increase of all the unwashed and 

 unmudded treees that he measured (93 trees in number of various kinds) was in 

 1779 but 6 feet 5-j^j- inches, or 77-^ inches, which gives but W and about -J- to 

 each tree; when in 1778 (a very dry summer in Norfolk) they increased near 85 

 inches, which gives above -^ to each tree: and this summer of 1780 being also 

 very dry, yet the aggregate increase was above half an inch more than in 1778. 

 But the best increase of these 3 years was low, as there were but 20 of the 93 

 trees that there were not planted by Mr. M., and greater increase is reasonably 

 expected in young than old trees; yet he had an oak '200 years old in 1780, 

 which was 16 feet and 5 inches in circumference, or 197 inches in 200 years. 

 But this oak cannot properly be called old. 



