4^8 
An Account of the Measurement 
Table for converting the Divisions shewn on the Micrometer Head 
into Seconds ; the Space subtended by 5 ' on the Limb being 
found = 5 Revolutions 45 Divisions , as deduced from the Mea- 
surement of the Total Arches. 
R. 
D. 
/' 
R. 
D. 
// 
O 
1 
1,002 
O 
30 
30,050 
O 
2 
2,003 
O 
31 
31.052 
O 
3 
3,005 
O 
32 
32,053 
O 
4 
4,007 
0 
33 33 »o 55 
O 
5 
5,008 
O 
3434,057 
O 
6 " 
6,010 
O 
3535,058 
O 
7 
7,012 
O 
36 
36,060 
O 
8 
8,013 
O 
37 
137,062 
O 
9 
9*015 
O 
38 
38,063 
O 
10 
10,016 
O 
3939 5 o 65 
O 
1 1 
1 1 ,0 1 8 
O 
40 
40,067 
O 
12 
12,020 
O 
41 
41,068 
O 
l 3 
13,022 
O 
42 
42,170 
O 
14 
14.023 
C 
43 
43,072 
O 
l 5 i 15,025 
O 
44 
44,073 
O 
16 
16,027 
O 
45 
45075 
O 
17 
17,028 
O 
46 
46,077 
O 
18 
18,030 
O 
47 
47,078 
O 
*9 
19,032 
O 
48 
48,080 
O 
20 
20,033 
O 
49 
49,082 
O 
21 
21,035 
O 
50 
50,083 
O 
22 
22,037 
O 
5 1 
51,085 
O 
23 
23,038 
O 
52 
52,087 
O 
24 
24,040 
O 
53 
53,088 
O 
2.5 
25,042 
O 
54 
54,090 
O 
26 
26,043 
O 
55 
55,092 
O 
27 
27,045 
O 
56 
56,093 
O 
28 
28,047 
O 
57 
57>°95 
0 
29 
29,043 
O 
58 
58,097 
