the Pendulum vibrating Seconds in the Latitude of London. 421 
~ The results of such of the preceding experiments as are to be 
used for calculating the length of the seconds pendulum, are 
brought under one view in the following table : 
- my) 
| Place | | No of vibra-) 4 No.of vibra-| Vibs. in} 
| of the Expt. [Temp. Barom,|tions. Great ¢ tions. Great/excess or 
| slider. wt. above. |2 2} wt. below. | defect. 
23 A | 68:7 | 29-76| 86059:39 —_ -03 | 86059-42 _ 
23 | B | 71-3 | 29-86| 86057-70 |-93 | 8605793 | — 
a} CC 71-4 | 29-86| 86057-93 | -23 | 86057-70 28 
93 | D | 73:1 | 99:95) 8605654 |.43 | 8605697 — 
| 
Pendulum remeasured. 
21 E 69°3_ | 29°70 | 8605888 | -06 | 86058-94 
F 69:3 | 29°70 | 86058-89 |-12 | 86059-01 
20 G 68-5 | 29°70} 86059:03  |°19 | 86059-22 
H 68-7 | 29°70 | 86059:36 |-11 | 86059-25 
69-3 | 29.70 | 86059-19 |:16 | 86058-93 
K 69°3 | 29-70 | 86059°14 |°31 | 86058-83 
19 L 68-1 | 29°90 | 86059°26 | °04 | 86059-22 
M | 68-4 | 2990) 86059-17 | -04 | 86059-21 
peseeece! 
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— 
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~ 
| Mean} 86055°7! | 86058-72 | 
No other explanation of this table appears to be necessary, 
than that the column entitled “¢ Difference” expresses the dif- 
ference between the number of vibrations in the two positions of 
P ns pendulum, and that the last column indicates by the sign + 
r — whether the number of vibrations exceeds or falls short of 
‘the truth; which inference is drawn from a comparison of the 
number of vibrations when the great weight is above, with the 
number in that position of the pendulum when the great weight 
is below. The mean of the vibrations in‘the column “ Great 
weight above” not differing sensibly from that headed “ Great 
weight below,” is a proof that the number of vibrations in either 
position of the pendulum may be considered as equal, and con- 
sequently that the one knife edge being the point of suspension, 
the other must necessarily be in the centre of oscillation. 
Length of the Pendulum vibrating Seconds, 
The distance between the knife edges was as follows : 
Inches. Divisions. — Inches. 
By the Ist measurement 39°4 +.956°47 =39°44094 
By the 2d, .. ws 39°4-4954-49=39-44086 
By the 3d, ee 39°4+ 955°65 =39°44090 
Corr. for error in division of the scale (see 
Oa pai RR iA — 000005 
3944085 
Dds Hence, 
