II PRELIMINARY GENERAL CATALOGUE OF STARS FOR IQOO 
gation in any critical problem requiring the most accurate available values either 
of the positions or motions of the stars. The records of observation then were 
too scanty to afford much hope that the best values of proper-motion which could be 
computed for the generality of stars at that time would have been very much better 
than rough approximations, or otherwise than very unsafe for the purpose of pre¬ 
diction. Practical considerations seemed to be opposed to any very great refine¬ 
ment in such computations; and accordingly no such refinement appears to have 
been attempted in the construction of the Catalogue of the British Association. 
Furthermore, owing to the amount of reliance placed upon the precision of star 
positions obtained from Lacaille’s zones (1750) and upon Taylor’s earlier results 
at Madras (which contained very anomalous errors in declination) the proper- 
motions of the far southern stars printed in the “B. A. C.” are wholly unreliable. 
In the first years after its publication the B. A. C. was doubtless used to a 
considerable extent for predicting positions of the stars to be used in problems of 
precision; but in the course of time it must have been distinctly seen that this use 
of the Catalogue was no longer justified. Yet the use and appreciation of that 
work scarcely waned during the first quarter of a century after its publication; and 
on many points it is consulted with advantage even yet. 
It seems worth while to have recalled these facts about a notable work in the 
history of astronomy, in order to throw into proper relief the remarkable fact that 
more than sixty years have elapsed since the publication of the B. A. C. without 
the appearance of a work, or combination of works, to take the place it once held. 
The construction of such a catalogue has been suggested from time to time in a 
tentative way, but seems always to have been regarded without definite encourage¬ 
ment. Apparently two ideas have operated effectively as the chief obstacles in 
carrying out the preparation of an extensive general catalogue of stars. The first 
has been that, pending the completion of certain works of meridian-observation, the 
time has not been ripe for the production of such a work. The second is analo¬ 
gous to this, viz.: that a general catalogue aiming to exhaust the existing material 
of observation upon the brighter stars (4,000 to 20,000 in number, say) would be 
almost necessarily out of date soon after its publication. Very quickly the need 
for a new edition would be felt, owing to rapid accumulation of further meridian- 
observations. But these objections, whatever force they may have against the 
construction of a star-catalogue chiefly for the sake of the star-positions it contains, 
would have far less force against the general computation of proper-motions. 
From time to time these are needed and must be had in various departments of 
astronomical research, and especially for the study of general stellar problems in a 
variety of forms. Therefore, the question whether it is worth while to construct a 
general catalogue of the principal stars becomes a question whether we shall incur 
the proportionally small additional labor and expense involved in putting general 
computation for proper-motions into the form of a published catalogue, after the 
main portion of the required computations has been effected for another purpose, 
of conceded utility. Perhaps the answer to a question like this can best be referred 
to the test of future experience. At any rate, it has seemed to the author that a 
great variety of uses would be subserved by the publication of such a catalogue. 
