From the latter
circumstance we may conclude that thaws often originate under
ground from warm vapours which arise; else how should
subterraneous animals receive such early intimations of their
approach? Moreover, we have often observed that cold seems to
descend from above; for, when a thermometer hangs abroad in a
frosty night, the intervention of a cloud shall immediately raise the
mercury ten degrees; and a clear sky shall again compel it to
descend to its former gauge.
And here it may be proper to observe, on what has been said above,
that though frosts advance to their utmost severity by somewhat of
a regular gradation, yet thaws do not usually come on by as regular
a declension of cold; but often take place immediately from intense
freezing; as men in sickness often mend at once from a paroxysm.
To the great credit of Portugal laurels and American junipers, be it
remembered that they remained untouched amidst the general
havoc: hence men should learn to ornament chiefly with such trees
as are able to withstand accidental severities, and not subject
themselves to the vexation of a loss which may befall them once
perhaps in ten years, yet may hardly be recovered through the
whole course of their lives.
Pages:
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427