TIDAL DATUM PLANES 91 
the use of tabular values. When tides are observed at a place remote from a suitable 
primary: tide station the range may be corrected by use of these tabular values. 
In the discussion of yearly high water it was found that the variation of high 
water above sea level is a function of the range of the tide and depends also on the 
relative amplitudes of the daily and semidaily tides. For the purpose of deriving 
factors to correct the range to a mean value, the ratio of the daily to the semidaily 
constituents is taken from the harmonic constants as (K,+0,)+M,. Where harmonic 
constants are not available this ratio may be derived, approximately from the formula, 
2(DHQ+DLQ)-=Mn, in which DHQ is the mean high-water diurnal inequality, 
DLQ is the mean low-water diurnal inequality, and Mn is the mean range of the tide. 
The derivation of the diurnal inequalities will be taken up in connection with the 
higher high-water and lower low-water datums. In Table 4 the ratio of K,+O, 
to M, at a number of points along the coasts of the United States is given. 
TaBLE 4.—Ratio of K,+0; to M2 
Atlantic Coast: Pacific Coast: 
Iasbport.e Vie. 2 oMues 8 yee 0. 10 Sane DicsouCalit. 322/52 aks ee 1. 00 
Rortlarid/ssMess 8 bee 2 ie 0. 19 Lay Jolla W@ aliens. 1oe so). .1 pec eet 1. 10 
BostonsaMassa 242.64 2 ee 0. 19 Los Angeles Harbor, Calif______ 10% 
Woods Hotes Mass2 a2 52. 222" 0. 56 Port Hueneme, Calif___________ 1.15 
Rrovidencen hissbe=s= sane. De 0. 19 San Francisco, Calif__.________ 1. 10 
New OnG. hi eae ae meee ees ade 0. 22 stockton) (Cahi. aie june sans 0. 84 
New London, 'Conn—_=- —_ 22. 0. 34 Humboldt Bay, Calif._________ 0. 98 
Ife was Vora Nia Yoo = eres ete Ee 0. 23 @rescent; City) Calif 3322 7 sees 0. 88 
PAU fost any aul Ngee cosh alee ae Shoei 0. 31 PortsOrfords Ore eee eee 0. 92 
Samehya Hooke Nie Je ee eters 0. 23 Coostbayeg Ore canes ee enor eee 0. 82 
Mulantic: City, Ne Je oe sso ee see 0. 30 ING wp Orts One eae ant eee 0. 80 
mnlerdelplniagibe a se eee 0. 22 INSLOTION OLE Gamal e ce ees eee 0. 66 
Mewes Dalen ue Wanke Saas S 0. 31 Grays Harbor; Wash__-__--_2=_ 0. 63 
BaibimOnes Vidar! 222 See oes 0. 74 INeallgB ayaa Was ee 0. 97 
AmmapoliserMideas fee see Bo 0. 80 Port Townsend, Wash_--_-______ 1. 82 
Washineton, Dose" 22042 0. 18 Seattle Washes.) ey joc <= 1. 20 
Rrehmond Vian se se. fe sae ets 0. 21 Olympian Wiashiss. 1) Sees eee 0. 93 
INontollct Wa 252 sere ee 0. 25 Friday Harbor, Wash__________ 2.13 
Walminetony Ne Clases Ss 0.26 | Alaska: 
SouthportwNe C2224 - = swe 0. 25 Wetchikangetshs ne seay feels Se 0. 44 
Charleston ss. C 224-5 2: eee 0. 24 unease. foo. so oe ee 0. 41 
SawanmaliynGas.2U Ue. Sai eys.g0s 0. 18 GLa ees Nee 4 db die et - 0. 67 
Wetvpontpilase a5 = 2 5ae ee 0. 22 Skagway a2 Wis Ue Sele samen 0. 41 
Daytona Beach, Fla_-_-----~-- 0. 30 MAU Cater lhe na oe See Neva 0. 65 
AVitepmaaeg hates 2 oe a) Peeper 0. 20 Cordovan gopher eS spo es ee 0. 56 
Gulf Coast: Seward asiges Lot) Sapa eee 0. 60 
KevaVVeSts bla a sO CEs eee 1. 03 NOG UW ea aE ee 0. 68 
@edar, Keys )Hla sou. 52 ee Se 0. 95 Dutch) Harbors) — seen eee 2513 
iRensacolay Hla 5.2 eas. Ae eee 12. 29 AG alee he 2 Ae a Ae ME Get aoe: 3. 66 
ING bilestAla ic us tae head 18. 60 ACC UNT tet BETES Bi vk SE 2555 
Byree ne: Weel fete, ih at ya aie 3. 34 St. Michaelbaswerun teas wale 3. 82 
Galvestonmilexs 22522 a ere 2.42 | Hawaiian Islands: 
Rockponty hex ies seer 2 oes 7. 35 Honoluluze eee ae eee 1. 36 
iRortdsabel\l ext as ese 4.12 Hilo 222 Aaa wee, ate G See ee eat 
It will be noted in Table 4 that the ratio of K,+O, to M; is approximately the same 
for large regions, so that at any desired point this ratio may be taken to be the same as 
at a station in the general vicinity. ‘Thus for the Atlantic coast of the United States 
this ratio is about 0.2 while for the Pacific coast it is about 1.0. On the Gulf coast 
this ratio shows wide variations but even here the value at any given point may be 
taken as characteristic of the tide in the near vicinity. 
The ratio K,+0, to M. may also be used as a criterion of the type of tide. In 
the section discussing the criteria for the different types of tide the formula used was 
