8 PREFACE. [Vol. XIV. 



Use," contains a collection of the formula to be used for any planet of the Hecuba group, the 

 general tables of the pertuibations which must be employed, and a more complete appUcation 

 of the formula; and the revised tables to the plane* (10) Hygiea, than v. Zeipel gives. The 

 second and more extensive section, entitled "Tables for the Determination of the Perturbations 

 of the Hecuba Groui> of Minor Planets," concerns the construction of the tables and their dis- 

 cussion with reference to the corresponding tables by v. Zeipel. It forms the preliminary part 

 of the in jestigation but is presented last as supplementary to the final results given in the 

 first section. 



In the second section the tabular values which differ from the corresponding numbers in 

 V. Zeiper,s tables are placed in brackets. The general Tables XXXV, XXXVIII, XLIII, 

 LIV, LVi, LVii, LVI, LVII, of the second section, which, in order, are required to compute 

 the perturbations of any planet of the Hecuba group, are repeated without brackets at the 

 end of the first section as Tables A, B, C, D, Ej, Ej, F, G, so that the first section is complete 

 in itself for use in developing the perturbations of any planet of this group without the necessity 

 of reference to the second section. 



A general account of the investigations of the perturbations of the Watson planets was 

 presented to the Academy on April 16, 1916, and is published in the "Proceedings of the 

 National Academy of Sciences," Volume 4, No. 12, March, 1919. 



Washington, D. C, 1918, December. 



Akmin O Leuschnee. 



