An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

'TlDES. 1.~7
ta ss and fall o\ward th]e l1moo. For a similar reasonl the waters ill tlhe opposite hlemlisphler falling less toward thle mloon
tlhal telt solitd eartl, are left betindl or appear to rise f'romll thle
center of thle arth.
28 1. xet )EFG- (tig. 56) rep}resent the globe; an(l, for tlhe
sake of illustratin g the principle, we will suppose thex waters
Centirely to cover1 the globe at a imiform de(pth.,Let dy/J, represent tlhe solid globe, and tle circular
rinl, exterior to it, thle covering of wa-ig
ters. Let C be the center of gravity
of the solid mafss, A thlat of the hemlisl)icre next to thle moon, and Bt thlat ii/
of the remtoter emisphelre. i'Now thle
force of attractionll exerted by thle
moont acts in thel same manler as
tloughl the solid tiass werel all concertntlrated in C, al(l the waters of each t!clinis.hetle at A\. andl BL rcspectiv\ly i;
and (the moon betilng stlpposed atbove I,4) it is evident that A
w\rill tentl to leave C, and C to le(ave 11 bellind. l'The samle nust
evidelntly be trutt of the respective p)ortiots of matter, of whlich
tlhese points are tlthe centers of gravity. ThI'e w\aters of tilhe glolbe
will tltus be reduced to an oval shrlape, tl)ing elotngated ill tlhe
direction of thtat meridian whtich is under the moon, andt flatte:ned in thle intermediate parts, and most of all at 13oiltts lilety
degrees distalt from tfhat Clridian.
Werel it not, therefore, for impediments which pl)exrelt thle
force from prodtcillng its full effects, we might expect to see
the great tlidr-waetw, as the clevated crest is eallCed, always
directly beneathl the mnoon1, attending it; regularly around thle
globe. IButlt tlhe inertia of the waters prevents tlheir inistanltly
obe ying the moon's attraction, and the frietion of tlhe wateirs on
tlh bottom of the oceanl, still futrther retards its,'togrcss. it is
not tllerefoire untl several houirs (differing at diftereni t pl(acws)
after thle moon has lpassed tlhe meridian of a place, that it is
htigh tide at that placo.
282. ThlIe san, has a, similar action to the moon, buit only,oe-thi/d as groat. On account of the great mass of the sunl