L E T T E R XLIV.
TO THE SAME.
Selborne*
« _ « I mm* m o n f t r e n t ”
« Quid tantum Oceano properent fe tingere foies”
« Hyberni; vel quas tardis mora no&ibus obftet.”
G ENTLEMEN who have outlets might contrive to make ornament
fubfervient to utility : a pleafing eye-trap might alfo contribute
to promote fcience: an obelilk in a garden, or park might
/ be both an embellilhment and an heliotrope.
Any perfon that is curious, and enjoys the advantage of a good
horizon, might, with little trouble, make two heliotropes; the one
for the winter, the other for the fummer folftice : and thefe two
erections might be conffirudted with very little e x p en fe fo r two
pieces of timber frame-work, about ten or twelve feet high, and
four feet broad at the bafe, and clofe lined with plank, would
anfwer the purpofe.
The ereftion for the former fhould, if poffible, be. placed
within fight of fome window in the common fitting parlour ; be-
caufe men, at that dead feafon of the year,, are ufually within
doors at the clofe of the day; while that for the latter might be
fixed for any given fpot in the garden or outlet •' whence the owner
might contemplate,, in a fine fummer’s evening, the utmoft extent
that the fun makes to the northward at the feafon of the longeft
days..
days. Now nothing would be neceflary but to place thefe two
objeBs with fo much exadtnefs, that the weßerly limb of the fun, at
fetting, might but juft clear the winter heliotrope to the wed of it
on the ßorteß day; and that the whole difc of the fun, at the longeft
day, might exadtly at fetting alfo clear the fummer heliotrope to the
north of it.
By this fimple expedient it would foon appear that there is no
fuch thing, ftridtly fpeaking, as a folftice; for, from the ßorteß
day, the owner would, every clear evening, fee the difc advancing,
at it’s fetting, to the weßward of the objedt; and, from the longeß
day, obferve the fun retiring backwards every evening at it’s feting,
towards the objedt weßward, till, in a few nights, it would fet
quite behind it, and fo by degrees to the wefl of i t : for when the
fun comes near the fummer folftice, the whole difc of it would at
firft fet behind the objedt; after a time the northern limb would
fir'ft appear, and fo every night gradually more, till at length the
whole diameter would fet northward of it for about three nights ;
but on the middle night of the three, fenfibly more remote than
the former or following. When beginning it’s recefs from the
fummer tropic, it would continue more and more to be hidden
every night, till at length it would defcend quite behind the
objedt again ; and fo nightly more and more to the weßward.
L E T T ER.