l8o REPORTS OF INVESTIGATIONS AND PROJECTS. 



Newcomb, Simon, Washington, District of Columbia. Grant No. 487. 

 Investigations in. mathematical astronomy, statistical methods, and 

 economic science. (For previous reports see Year Books Nos. 2, 3, 4, 

 5, and 6.) $5>ooo. 



Dr. Newcomb reports the following: 



Completion of the Equations of Condition from Occultation of Stars by 

 the Moon from 1672 till the Beginning of 1908. The solution of the equa- 

 tions is in progress, and the discussion of results includes not only the ele- 

 ments of the moon's motion, but other fundamental astronomical constants 

 pertaining to the sun and stars. The long delay in bringing this work to a 

 termination has arisen partly from the necessity of introducing many correc- 

 tions in the older work and from the inclusion of a great number of addi- 

 tional observations, especially those of recent years. This study shows 

 beyond serious doubt that the motion of the moon is subject to fluctuations 

 for which no known cause is adequate to account. 



Corrections to Oppolzer's Tables of Eclipses, with a view of using them 

 in a general rediscussion of ancient eclipses of the sun. 



Continuation of the work on the theory of probable inference, as applied 

 to the derivation of results from observations of a statistical character. 



Preliminary studies of the perturbations of Mars, with a view to new tables 

 of that planet. It is hoped that this work will be continued under the 

 auspices of the Nautical Almanac Office. 



A paper on the "Best form for new tables of the moon" was issued in 

 the Monthly Notices of the Royal Astronomical Society, June, igoS, and an 

 article on the "Investigation of the fluctuations in the temperature of various 

 regions of the earth since 1820" was published by the American Philo- 

 sophical Society during the past year. 



A resume of the history and present state of the lunar theory was read 

 before the Congress of Mathematicians in Rome in April. 



Russell, Henry N., Princeton, New Jersey. Grant No. 207. Photographic 

 determination of stellar parallaxes. (For previous reports see Year 

 Books Nos. 3, 5, and 6.) $1,000. 



In this work the photographic observations, continued at Cambridge, 

 England, by Mr. A. R. Hinks, have been completed. The whole number of 

 plates used is 258 of 38 different fields; 161 of these were obtained by Dr. 

 Russell and 97 by Mr. Hinks, and all have been measured by Dr. Russell, 

 and the measures completely reduced. 



For 31 series observations were obtained at from 3 to 6 parallactic epochs. 

 These series include 220 plates, with a total of 853 exposures, and upon 

 these plates 7,899 images of 287 stars have been measured. The parallaxes 



