Use of the Zenith Telescope in Determining Latitudes. 193 
readings of the level as N. and 8. ends, instead of object and eye- 
ends, some trouble is saved. ‘The table, with its headings, is as 
above. 
Of the arrangement of the instrument in its place, and the 
7 - 
when near its culmination. Another method, introduced by As- 
NUMBER IL. 
Values of Micrometer Divisions, No. 1, by Distant Mark. 
Daa) Disance | With Micro] Wink Theatie wane | a alt 
peg] from ___ meter, a, one sles, ae 
ivis. 
May 16, | o's § | rax308| 4631 |” ‘36t8 | -0004 | ~oon090r8 
Cre W +: edad 503-2 +3800 s oe 
0% A 2845-0 109°6 +3152 
ns |__| ——<—<——__ : 
e==0!l-0051== probable error of a single ration. 
E=0 -oo1r2==—* “ mean of all. 
__Mean value of one division of micrometer ==0'"380SH01 0082 
pairs N. and S. of the zenith, zero. It is, generally, convenient 
to approach nearly to the fulfillment of this condition. 
Stooxp Szrues, Vol, XIV, No. 41.—Sept., 1852. 25 
