228 EVAPORATION OF EVEKGEEEiN AND BECIDUOTIS TKEE3. 



Zinc pots about 20 inches deep and 36 inclies in circumference 

 M^ere filled with good garden mould, mixed with loam, and a tree 

 was planted in each on the 22nd of December : they weighed 

 about 42 lbs. each ; on the surface of the pot a zinc plate was 

 fixed, having a liole to admit the stem ; these plates did not fit 

 very close, and a certain amount of the water evaporated is due 

 to this cause. Towards the end of April a piece of oilskin was 

 placed over the zinc plate, being fastened round the stem of the 

 tree by India rubber string, and also around the pot below the 

 opening with an elastic band, which effectually prevented allescape 

 of water except through the trees. The plants were placed in an 

 open shed protected from the rain, and were supplied with water 

 from time to time as they seemed to require it ; the weights 

 were taken by means of the apparatus described in the Journal of 

 the Horticultural Society of January, 1850. Upon referring to 

 Table I. it will be seen that a considerable falling off in the 

 water evaporated is apparent at the period when the oilskin was 

 put over the openings and the air perfectly excluded. Part of 

 the plants were covered April 14th, and the remainder April 

 24th ; it appears to me probable that the reduction in the water 

 evaporated is not entirely due to the water being prevented from 

 escaping through the hole in the lid, but it is partly due to an 

 injurious effect upon the plant itself, some of them having 

 evidently suffered. With the exception of the Ilex, which de- 

 clined from the commencement, and appeared to be dead, or 

 nearly so, in the spring, all the plants are alive at this tune, but 

 not equally healthy. The Yew has been perfectly healthy all the 

 year ; shoots about 2 inches long have been produced from each 

 stem ; it is quite as vigorous as one exactly similar planted in 

 the garden. Evergreen Berbery, perfectly healthy, lost all its 

 leaves in the spring, and produced fresh ones q\nte equal to that 

 in the garden. Portugal Laurel, about the same as when planted, 

 has not grown. Connnon Laurel, a great many leaves fallen at 

 various times, which have not been reproduced ; the garden 

 plant much healthier. Spruce Fir produced young shoots about 

 2 inches long, which are now green, but the remainder of the 

 plant is brown, and I should think would die, if not removed. 

 Holly very healthy, a little grown, quite equal to the garden 

 plant. Larch grew well at first, but in the summer the leaves 

 were covered with spots of turpentine, and the colour of the leaves 

 was unhealthy ; I should doubt whether it would live another 

 year. Sycamore tolerably healthy, but some of the leaves mil- 

 dewed. Oak and Ash about the same, tolerably healthy. Ber- 

 beris D. healthy all the year. Table No. II., in which the water 

 evaporated is divided into periods of four months, shows very 



