Dr. Young’s Hydraulic Investigations. vji 
Table of Coefficients for French Inches. 
d 
a 
• 1 7 X 
c 
• i 7 X 
d 
a 
• i 7 X 
c 
.1 7 X 
d 
a 
•l 7 X 
c 
,i 7 X 
d 
a 
•J'X 
c 
• i 7 X 
00 
43 ° 
900 
40 
400 
719 
4 
3*9 
540 
•4 
257 
* 7*7 
500 
427 
943 
3 ° 
393 
618 
3 
305 
617 
* 
268 
1895 
400 
426 
946 
2 5 
3 »7 
560 
2-5 
296 
687 
•3 
2 79 
2008 
300 
4 2 3 
950 
20 
380 
492 
2 
288 
751 
1 
z 
3°3 
2225 
200 
421 
95 * 
! 5 
37 ° 
427 
*•5 
275 
865 
.2 
349 
2532 
IOO 
416 
9 2 3 
10 
354 
4*4 
1 
259 
1063 
I 
IT 
402 
2827 
9 ° 
4 i 5 
911 
9 
35 ° 
421 
•9 
255 
1123 
•*s 
440 
3026 
80 
4 i 3 
896 
8 
345 
433 
.8 
252 
1 1 93 
1 
T 
458 
3116 
70 
410 
872 
7 
340 
440 
•7 
249 
1278 
1 
3 * 
518 
34°5 
60 
408 
840 
6 
335 
462 
.6 
248 
>384 
i 
S89 
3693 
5 ° 
406 
792 
5 
325 
513 
•5 
249 
1524 
,1 
646 
3985 
For example, in the last experiment, where d is 1, / 4, and 
627.1, we have a = .0000259, b = d + * = 516, c = 
.0001063, e = bcl:d== . 22, and — ^ = 118.46, 
which agrees with the experiment within -3-^- of the whole. 
I had at first employed for a the formula ■ + 4 [ 1 ° - - ^ + 2Z + 
but I found that the value, thus determined, became too great 
when d was about 20, and too small in some other cases. 
Coulomb’s experiments on the friction of fluids, made by 
means of the torsion of wires, give about .00014 for the value 
of c, which agrees as nearly with this table, as any constant 
number could be expected to do. I have however reason to 
think, from some experiments communicated to me by Mr. 
Robertson Buchanan, that the value of a , for pipes about 
half an inch in diameter, is somewhat too small ; my mode of 
calculation, as well as Dubuat’s, giving too great a velocity 
in such cases. 
If any person should be desirous of making use of Du- 
buat’s formula, it would still be a great convenience to begin 
Z 2 
