68 
ASTRONOMY: A. 0. LEUSCHNER 
member of the board of Watson Trustees; later he became chairman of the 
board, and remained in that capacity on the board until his death in 1908, 
being succeeded by Prof. E. C. Pickering, whose associate trustees now are 
Professors E. B. Frost and W. L. Elkin. The National Academy of Sciences 
through its various boards of trustees has at all times made the most per- 
sistent efforts to discharge the chief obligation imposed by the trust, by 
providing tables of the perturbations of the Watson asteroids. 
My own connection with this great undertaking is best explained by the 
following substance from a letter addressed to me by Professor Newcomb 
under date of June 4, 1901. 
I have consulted with the Watson Trustees on the subject of having the perturbations of 
certain Watson asteroids computed under your direction. We are all favorable to the pro- 
ject provided we can have some assurance of success. We have had the cooperation of many- 
capable men but so far the result has not been satisfactory. The general outcome of the 
matter is that we are supplied with a mass of papers, computations, perturbations, and 
perhaps tables, but nothing has yet reached us in a form complete and perfect for publica- 
tion as tables. We had just about reached the conclusion that the work must be done here 
at Washington under my personal direction and according to formulae which I should supply. 
For further details in regard to the earlier history of the work I must refer 
to the introduction written by Professor Newcomb in March, 1908, to the 
tables of twelve Watson planets completed under my direction in 1907 and 
published in 1910 as volume X, Seventh Memoir of the National Academy 
of Sciences. 
Actual work was commenced by myself with the assistance of Drs. Russell 
Tracy Crawford and Frank Elmore Ross according to a somewhat definite pro- 
gram carefully arranged by Professor Newcomb. Our investigations were 
to be confined to those thirteen planets, for which so far no attempt for deri- 
vation of the perturbations had been made. Professor Newcomb's purpose 
being to have the difficulties encountered with the remaining planets inves- 
tigated under his personal direction at Washington. One planet, (132) 
Aethra, was to be entirely excluded from the program, having remained lost 
since the year of its discovery in 1873. But in April, 1903, it was agreed that 
all the previous investigations should be turned over to me. At the same 
time it had become apparent that the success of the undertaking demanded 
that I should be given the utmost freedom in planning and conducting the 
investigations, to which the trustees readily consented. 
Today it is my great privilege to be able to report to you, that except for 
the completion of the manuscript for pubHcation, and some minor numerical 
work, the task is accomplished and that the obligations of the National Acad- 
emy under the Watson Trust pertaining to the perturbations and tables of 
the minor planets discovered by Watson, will soon be fully discharged. 
It is impossible in this brief space of time to give a complete history of the 
work, including the part taken by my numerous assistants. I must also refrain 
from reporting on the many scientific results attained as to methods of attack 
