Towns > Glasgow > 1828-1912 - Post-Office annual Glasgow directory > 1848-1849

ALMANACK AND TIDE T^BLE.
Jui.y, 1848, TUX July, 1849.
On the subject of the TJdfes, we may remark tfiat they ave effected by
the unequal, attraction of the sun and moon, but chiefly that of the latter
object. The times of high water do not always answer to the same
distance of the moou from the meridian at the same places, but are variously
affected by the action of the sun, wliich brings them on sooner when tba
moon is in her first and third quarters, and keep^ them back later when she
is in her second and fourth; because, in the former case, the tidea, raised
by the sun alone, would be earlier than that raised by the moon, and in the
latter case, later. Wiien the moon is in perigee, or at her nearest distance:
from the earth, she attracts strongest, and therefore raises the tides most^
the contrary happens when she is in apogee, or at her greatest distance frora
earth, because of her weaker attraction. At new moon, when the moon la-
in; conjunction with the sun, the tides ai'e raised by the joint attraction of
both Inminaries, and therefore will be highest; the same is the case at full
woon, when the sun and moon are in opposition; for whilst the moon raises
tb? tides under and opposite to her, the snn, acting in the same line, raises
the tides under and opposite to him, whence their conjoint effect is the same
as at the change, and in both cases occasion what are called Spring Tides.
But at the, quarters, the sun raises the tides when the moou depresses them,
and depresses them when they would be raised by the moon; hence it is
the difference of their actions that produces the tides at the quarters, and
these are called Neap Tides. But these tides do not happen till a day or
two after the abore times; because in this, as in other cases, the effect is
not greatest or least when the immediate influence of the cause is gi'eatest or
least, but sometime afterward.
The sun being nearer the earth at the beginning than at any other time of
the year, his attraction will then be most powerful, and of course, about
January, the Spring tides will be gi-eater than at any other time, and great-
est of all if the moon at the same time happen to be in perigee.
When the moon is in the equinoctial, the tides are equally high in both
parts of the lunar day; but as the moon declines from the equinoctial towards
either pole, the tides are alternately higher and lower at places having
north or south latitudes. Whilst the moon has north declination, the great-
est tides in northern hemisphere are when she is above the horizon, and the
reverse when her declination is south. The time and elevation of high water
at Glasgow, are considerably affected by high winds in the Clyde. From
the form and course of the Frith, it Avill be easily seen that a gale from the
N.N.W. or N.W., by opposing the flow of the tide, will cause the time of