83 
1845 ; and examination has shown them to ‘possess decided 
value, in spite of the very unfavorable circumstances under 
which they were made. During the remainder of the year he 
was occupied with the adjustments, and in determining the 
Instrumental errors, of the Meridian Circle. The thorough 
description of this instrument and discussion of its correc- 
tions, in the volume for 1846, is from his pen; as also is 
the description of the Prime-Vertical Transit. Nearly one 
ousand observations with the Meridian Circle in 1846, as 
well as the discussion already cited, give token of his ac- 
tivity ; but the equal labor of endeavoring to train and 
instruct many others, — who were assigned to duty at the 
several astronomical instruments by the naval routine, al- 
though not inclined to astronomical pursuits, and indeed 
often affected with distaste for them,— does not appear. 
Nor is any mention made of the careful and laborious organ- 
ization and inception of a system of zone-observations, admi- 
rably devised and arranged by one of our present colleagues 
in connection with Professor HuBBarpD, although no public 
acknowledgement of their services in this respect was ever 
made, nor indeed claimed, by either of them. According to 
the plan of these zone-observations (Washington Obser- 
vations, 1845, App., p. 32), the micrometers of the Mural 
Circle, Transit-Instrument, and Meridian Circle were pro- 
vided with additional declination-threads ; additional transit- 
threads were inserted in the field of the Mural Circle, and 
the micrometer of the Transit-Instrument was rotated 90°; 
thus rendering it available for the measure of differences 
of declination. ‘The several zones were made to overlap by 
10’ in declination, and the instruments were to be employed — 
simultaneously upon nearly the same declination, so that a 
* portion of the stars observed by the Mural and Transit should 
be identical. Thus the Transit-Instrument would give stand- 
