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

of tlhe earth1 att one. I'lhus at tlhe same time it is hliglh tide at
ally given place, it is also high tide on thele inifrior melridian,
and( thLe same is trueli of the lo'w tides...hle interval )betweenC to successive lhight t'ides is I.21h. 25111.;
or, if the sanme tfide 1)e colsideredl s returning to tlre nllri(ian,
after latving gone arontl tile globe, its retuttIrn is about 50 nmillntes later tlhan it occurred onl thle preceding day. Inl this respect, as \well as in various otlhers, it corresponids very nearly
to the motions of the moon.
Tlh1e avera c e heiglt fob tile whole globe is aboutlt 29 feet; or,
if the earth were covered mlliformlly with a stratum of water,
the dliflerencc betwcen the tNwto dialntctelrs of thle oval wtould be
b feet, o01r more exactly 5 feet and 8 inclhes; but its natural'
] aeqlit at various places is very if lferent, stomeltilmes rising to (O
or 70 feet, and1 sometimes being scarcely perceptible..At tlle
same lt lace, also, thle phllenomena of the tiles are very di;ffirent
at ditlleret tiimes.
Inland lakes and seas, even those of thle largest class, as'Lake1
tperiolr, or tihe Caspian, have no perceptible tide.
280..'7fdes ar'e eautsed Iby the tceqluail attt aetiont of t/he san,.
antd.mooin ~i on d[zl eaztetjParts qof the ear/th.
Supp)ose the projectile force byr w\\ich the earth is carried
orwal l ill her orblit to be sul)ellde(, <and thle carthl to faill
towtard one of these bodies, the moon for example, in consequence of tleir mutual attraction. T'leCI if all parts of tlh(
carttl fell equally toward thle moon,o derangementle l of its di-t
ferent parts wrould result, any more than of thle particles of a
drop of water ill its descent to thle ground. In!ttt if one paItl
fe11 faster than another, tlhe dil'erent portions would evidently
be sep)arated fronm each otiher. iNtow thlis is )precisely whatl takes
p)lace with resp)ect to the earth in its fall towatrd the lmon..t'lhe p)ortions of tile earth in tile hemisplere next to thle t10moon,
oil accounlt of l)eing n. arer to the centert of attraction, fitll fatste
thlan tlhose il tlhe opp site ]hemislphere, and consequently leave
themlll b)ehind. Te solid earth, onil account of its colclsill, can
not obl)e t1his im11ulse, siinee all its different portions constitute
one mass, wltichl is acted onl ill the same mannel l as thou1gh it
were all collected ill the ccnter; but thle waters on the surfXace,
mIoving, f'reely ulder this impulse, endetavor to desert the solid