the cube , cylinder , fisfc. 6y the late Sir G. S. Evelyn. 323 
meter screw, which passed through one of the sides of the 
square, was brought in contact with the diameter of the 
sphere, and the reading of the micrometer head noted. The 
sphere being then removed, a brass rule of known length 
was put in its place, and the micrometer screw being brought 
in contact with the end of the rule, the difference between 
its length and the diameter of the sphere was obtained, from 
which the latter could, of course, be readily determined. 
Sir George Shuckburgh had drawn three great circles in 
pencil upon the sphere, which, as well as the letters desig- 
nating their intersections, remained perfect. 
Having arranged the apparatus, the following measure- 
ments of the diameter of the sphere were taken, two of which 
may be termed equatorial, and the third polar, every pre- 
caution being used to prevent errors arising from difference 
of temperature. 
j.38,5 mean. 
The rule being now placed in the square, the following 
were the readings of the micrometer on different trials. 
51 , 5 " 
5i,5 , 
51 >51,33 mean. 
51 ,sj 
Hence, the diameter of the sphere exceeds the rule 12,83 
divisions. 
Diameter of 
the Sphere. 
Readings 
of the 
Micrometer. 
A to B 
C to D 
E to F 
37 
38,5 
40 
MDCCCXXI. 
Tt 
