various British standards of linear measure. 83 
This portion of the line being estimated, transverse lines 
were drawn, indicating the points from which future measure- 
ments were to be taken. 
On the 14th of April I resumed my comparisons. 
Conceiving that it would be preferable to ascertain the dif- 
ference between some one interval and the mean of all the 
intervals of Mr. Ramsden’s bar, and afterwards to compare 
such interval with the forty inch bar, I now directed my at- 
tention to this object. 
Fourth comparison. Thermometers 52 °,5. 
Readings. 
1st. interval 
99 >° 
2d. 
78,0 
3d. 
73 >° 
4th. 
83,0 
5th. 
82,0 
6th. 
83,0 
Mean 
83,0 
15th April. Fifth comparison. Thermometers 56°. 
Readings. 
1st. interval 
107,0 
2d. 
8l,0 
3d. 
76,0 
4th. 
89,0 
5 th. 
77 ,o 
6th. 
87,0 
Mean 
86,1 
