A NEW EVAPORATION FORMULA 
91 
Table 30 — Forms of observation equations used in last seven least-square solutions on Lakes Michigan-Huron 
and Superior for determining evaporation 
Designation of solution 
Lake 
Form of observation equation 
Vi* 
Michigan-Huron 
Michigan-Huron 
Michigan-Huron 
Michigan-Huron .... 
Superior 
eEi+ 
eEi+ 
eE.-r 
e£"i+ 
e£"i+ 
eJEi+ 
• Jfc+| 
/ xv \" 
e \wo- 2A ) 
- / w y 
J Vloo -2-V. 
/ xv \~ 
z e \m ~ 2& ). 
j Vloo -2-V. 
/ XV \~ 
Awo- 2A ), 
/ xo \" 
L c Vioo " 2 V. 
. Us- 2 - 8 A 
E,+I = v 
£"2+7 = 
£"a+7 = r 
£" 2 +7 = » 
Ei+[e (j^ -2.4)'] £, + 7 = t 
£"j+7 = c 
£" 2 +I = » 
V, 
v A 
V, 
BBi*-f 
BB, 
Superior 
BB t 
Superior 
t The term I e ( TqT. — 2.4 ) I E 3 was omitted for all wind velocities above 10.0 miles per hour. 
* In these two solutions, the wind travel, w, included all winds, both above and below 240 miles per day. 
are shown in Tables 30 and 31. Table 30 shows the seven final forms of the obser- 
vation equations used on Lakes Michigan-Huron and Superior, and Table 31 shows 
the derived values of the constants E it Ei and E, with their probable errors, and 
other pertinent data. The evaporation, in terms of e, computed from results 
shown in Table 31, is plotted on the upper part of Plate 6. 
Referring again to Table 30, note that the observation equations shown are all 
of the same form, with certain exceptions as to detail. The following is a brief 
characterization of the differences in the forms of equations there shown. 
The equation for Solution F 6 has already been presented in detail, culminating 
on page 81. 
(a) The form of observation equation for Solution V t was identically the same 
as that for Solution V b . Solution V t differed from Solution V b in that it contained 
Table 31 — Principal facts from last seven least-square solutions for determining evaporation 
Designation 
of solution 
Lake 
E: 
E, 
£-» 
No 
days 
of 
obser- 
vation 
No. 
of 
obser- 
vation 
equa- 
tions 
used 
Probable 
error of a 
single ob- 
servation 
of change 
in eleva- 
tion of 
mean lake 
surface 
from one 
day to 
next 
Mean 
JW 
V, 
M-H 
M-H 
M-H 
M-H 
S 
s 
s 
+0.448=0.034 
+ .224= .038 
+ .311= .034 
+ .266= .031 
- .045= .059 
- .275=fc .060 
- .154= .052 
+0.367 = 0.063 
+ .661= .085 
+ 1.019= .153 
+ 1.272= .148 
+ .925= .153 
+ .857= .138 
+ 1.163= .234 
842 
842 
842 
818 
847 
847 
847 
778 
774 
773 
755 
759 
756 
754 
= 0.016 ft. 
= .016 
* .016 
= .014 
= .021 
= .021 
= .021 
562 
553 
554 
455 
1007 
998 
1006 
428,852 
418,527 
422,226 
343,587 
700,553 
752,109 
754,954 
V t 
Vi 
Vt 
+0.803 = 0.264 
BBt 
BB, 
BB, 
