ADVISORY COMMITTEE ON ASTRONOMY 121 



might even be supplied with instruments temporarily borrowed from 

 some northern observatory. 



In general, that class of investigations in this department of as- 

 tronomy, which require some degree of departure from existing 

 routine, are very likely to require attention at times through sup- 

 plementary aid. The whole subject is one well worth)' of the 

 attention of the Carnegie Institution. 



Deduction from Meridian Observations. 



The obser\'er in this department of astronomy corresponds very 

 well with the skilled collector in the various branches of natural 

 history. The obsen/ations, which have been accumulated for more 

 than a centur}-, must be collated and compared. They must be 

 brought to bear upon the solution of physical problems. They are 

 dead material until they have been used in this way. Very little 

 has been done with this vast mass of precision observations in the 

 way of bringing its results to bear upon questions concerning the 

 motions of the stars, the motion of the Sun through space, and the 

 structure of the sidereal universe. The answers to a variety of 

 most important (questions in cosmogonjv' that are propounded and 

 vaguely discussed lie bidden in that mass of material, answers which 

 verj- probably may bring us only a few seeps forward, but which are 

 certain to accomplish as much as that. 



Comparatively little is yet known about the motions of the stars. 

 Not one-tenth of the available observations has been brought to bear 

 on that subject. Scarcely a greater percentage has been utilized in 

 the discussion of the all-important constant of precession, and the 

 same is true as to that problem of most absorbing interest — the solar 

 motion. 



Within the last three years the immense work of collecting and 

 comparing this mass of meridian observations has been undertaken 

 by Dr. Ristenpart, under the auspices of the Berlin Academy. Ex- 

 perience will show that this work must be continuous, since it will 

 no sooner be completed to a certain date than the necessity will aris^ 

 for extending to a later one. Yet it is from work like this that we 

 must denve nearly the whole of the benefit to the progress of as- 

 tronomy which is to be expected as the ultimate reward for the 

 immense energy which has been expended in making meridian obser- 

 vations of precision. 



For many years a similar collation and comparison has been in 

 progress at the Dudley Observatory of Albany, restricted to stars 



