issith preliminarij Observations on Climate. 545 



sufficient to effect the usual diurnal transition or expansion of 

 the cold vapour in the lower stratum of the atmosphere, which, 

 consequently, remained almost stationary, night and day. near 

 the surface of the earth. (Influenza, at the same time, became 

 exceedingly prevalent ; but, whether originating in, or being 

 connected with, this unusual state of the atmosphere, although 

 a seeming consequence, is not pretended to be affirmed,) Tlie 

 progress of vegetation was, for the greatest part of the month, 

 more effectually arrested than it was, perhaps, ever known to be 

 in April. From the steady cold, it was much in the same state 

 as a clock, of which the pendulum had ceased to oscillate; or 

 it was in a similar state to that in which exotics sometimes are 

 made to linger, or may be positively destroyed, by ill-directed 

 care ; that is, their being kept in a state closely apjiroaching to 

 uniform temperature : for it would probably not be too much 

 to affirm, that, if any species of vegetation, except, perhaps, 

 some of the cryptogamous plants, were kept at an undeviating 

 temperature, whether high or low, or even corresponding witli 

 the mean of the natural climate of the individual, such would 

 eventually die prematurely. Differently constituted species, of 

 course, admit not only of greater or less mean temperature, but 

 also of a greater or less range. Thus, an inhabitant of a shel- 

 tered situation, in the bosom of a wood, whei'e it never suffered 

 the full effects of the noon-day heat, nor the midnight cold, 

 would not thrive if removed to a situation where it would be 

 subjected to both these vicissitudes, alongside of the thriving 

 productions of the open fields. 



It would tiierefore appear to be desirable, if the range of 

 temperature in shady woods, compared with that of the open 

 country in the same latitudes, were better known. It may, 

 indeed, be questionable, whether a single instance is on record 

 of such being any where known at the present time ; not even 

 within those tropical forests on the tops of which the sun darts 

 perpendicularly his fiercest rays, yet cannot penetrate directly 

 through the dense foliage to the thus sheltered vegetation below, 

 amongst which the interesting tribes of Orchidaceee flourish. 



The digression into which I have been led from some remarks 

 connected with the peculiar state of the atmosphere in April is, 

 1 fear, already of inexcusable length ; and 1 can only hojie to 

 be excused for not directly returning to my subject by endeavour- 

 ing to submit to the consideration of the reader some farther 

 observations, which may be improved on, so as to tend, in some 

 degree, to the obviating of existing difficulties in regard to cer- 

 tain points in horticulture. 



It would be well if the ranges of temperature of summer and 

 winter, and of day and night, were more accurately known as re- 

 lates to plants brought under cultivation ; for then the limits of 

 Vol. XIII. — No. 93. n n 



