Letter from B. A. Gould. 467 
75°, between which declination and 80° only one series was taken. 
These widths were always halved within the limits of the Milky 
Way, and still farther subdivided into quarters, and even eighths, 
where the richness of the region required; so that some zones 
have only comprised 20’ or 25’ of declination exclusive of their 
marginal overlap. The maximum number of stars contained in a 
Single zone is 293, the average is about 140. It is needless to say 
that there are many repetitions, arising not only from the overlap, 
(usually 10’ at each margin), and five or six minutes of time at the 
beginning and end), but also from the re-observation of such zones 
as had proved unsatisfactory, whether from unfavorableness of 
weather, insufficient determining stars, or inadequate performance 
of circle, chronograph or clock. 
been my unfailing rule to make the determinations as 
hometry, whose positions have not been independently deter- 
mined in Cérdoba. I pu 
forward, and have now extended the working list yet more, SO 
that this catalogue will contain more than ten thousand stars, if all 
oes 
times, Up to the present time the total amount of different stars 
observed for this catalogue exceeds 7,000, although not all of them 
ave as yet the requisite number of observations. 
Besides the data thus collected I have a considerable amount of 
i from ted observation of clusters. 
These observations, when properly reduced, will essentially aid 
the study of the photographic plates. 2 
_ Now [ must apply myself to the more laborious and difficult 
Part of the work—the computation and preparation of the crude 
Material obtained. This would be more difficult everywhere as 
requiring a more unremitting diligence, and careful organization, 
