36 
BULLETIX 8-54, "T. S. PEPAETMEXT OF AGEIClTLTmE. 
Let (V. ^ir' Bj., and C\, A^. B^, be the F and s coordinates, respec- 
tively, of the above centers of gravity. The calculations for these 
coordinates are as follows : 
No. 
Log t: 
Log .'. 
417 
423 
429 
435 
442 
448 
461 
467 
0.5041 
.7847 
.9884 
1.204 
1.697 
2.1676 
2.7711 
3.0o5S 
0.0005 
.0010 
.0020 
.0030 
.005 
.0075 
.012.5 
.0150 
9.70251" 
9.894704 
Suin= 39.672744 
QQiQ^^ >Meaii= 9.918186= B t 
l5:S95j-^tilog.B.=0.8283 
10.2296S21 ^ ^^ 
10.335979'"""^ = 
10.442652 
.301030 
Simi= 28.477121 
-S^ lMean='7.ll9280= 5, 
10. 
,--15um= 41. 493438 
Mean= 10.373359= 
||g{^3AiitUog^r= 2.3624 
7 477m) -^iitilog £g= 0.00131S1 
S 170091 1 -^ii^ilog ^^0.0091571 
Suin=S1.1661S2 
Mean= 10.1457727= Cv 
Anttlog Cv=l. 
SuirL= 60.3241.53 
Mean=7.W0519= Cs 
Antilog a^= 0.0034715 
Since 
-4,--^r 
Cr-Br 
Cs-Bs 
aO.373.350 — 10.14.57727= 0.227.5'=ti 
= 10.1457727- 9.91Slb6 = .2275S7 
: 7.96175S — 7.540519 = .421239 
: 7.540519 — 7.1192S0 = .421239 
A -C 1 -C 
the tliree points, A, C, and B are hi a straight line, which checks the 
accuracy of the work (see American Civil Engineers' Pocketbook, 
second edition, p. S48^. 
The exponent, z. of T^ in formula 14. is the inclination of the hne 
ACB, and is equal to the tangent of the angle formed by the line and 
the unit\ axis of T^. 
A, -B, ^ 0. 8^2478 
A,-B„ 0.455173 
= 1.8509=2 
The intercept, m. is determined as follows from equation 15, using 
the coordinates of the center of £:ravitv, C: 
Log m- = log 5' — z loo; y 
= 7.540519 - 1.8509 X 10.1457727 = 7.270709 
and m =0.0018651. 
(19) 
The exponent of T' and the value of ni are found in the same man- 
ner for the other sizes of both concrete and clay tile, running nearly 
fuU. These values are shown in colunm 7 of Table 6. This table 
gives the formula derived as explained above for each size of tile as 
well as the range of velocities used in the derivation. 
