THE SMITHSONIAN INSTITUTION. 165 



out this assistance, the expedition would have been delayed a year. I 

 am now, however, happy to state that the expense of these instruments 

 has since been paid by an appropriation of Congress ; and the Institu- 

 tion has thus been the means of promoting the objects of the expedition 

 without any expenditure of its income. Certain improvements in as- 

 tronomical instruments, however, have been made since the departure 

 of Lieutenant Gilliss which would much facilitate his observations, and 

 enable him to do much more with his small number of assistants ; and 

 it may be well for the Institution to furnish him with instruments of this 

 kind. 



Under the head of researches it may also be mentioned that, during 

 the past year, we have caused to be computed, at the expense of the 

 Institution, an ephemeris of Neptune, giving the position of the planet 

 in the heavens from August 4, 1846, to February 4, 1848, and also in 

 the last half years of 1848 and 1849. This ephemeris is based on the 

 orbit of Neptune established by Mr. Walker and corrected by the per- 

 turbations of the planet Neptune by the action of Jupiter, Saturn, and 

 Uranus, as deduced from the mathematical investigations of Professor 

 Peirce, of Harvard University. 



We have distributed copies of this ephemeris to all persons known 

 to us who are interested in practical astronomy, not only in this country 

 but in Europe. It has been received with high commendation, and is 

 found to give the actual place of the planet in the heavens within the 

 limits Of a few tenths of a second of arc ; indeed, the coincidence of the 

 calculated and observed places is so marked, that, were the actual 

 planet of the heavens and that of the ephemeris to be considered as a 

 double star, they would have so close a proximity that no telescope yet 

 constructed could separate them. __ 



Occultations for 1850. 



A set of tables in continuation of those mentioned in the last and 

 preceding report for facilitating the calculation of the appearance of 

 occultations of fixed stars by the moon during the year 1850 has been 

 prepared by Mr. Downes, of Philadelphia, and published by the Insti- 

 tution. At the last session of Congress an appropriation was made for 

 establishing a Nautical Almanac, which will furnish, among other aids 

 to astronomical observation, sets of tables of the kind just mentioned. 

 Lieutenant Davis, of the United States navy, to whom the superintend- 

 ence of this national work has been entrusted, recommended that the 

 expense of the preparation of the tables for 1850 should be defrayed 

 from the appropriation for the Almanac ; and this recommendation has 

 been concurred in by the Secretary of the Navy. The Institution has, 

 therefore, been called upon merely to pay for the printing and distribu- 

 tion of the tables, and thus again enabled, with a small outlay of its 

 funds, to afford important facilities for the advance of science. 



Meteorology. 



Under the general head of researches we may also give an account 

 of the progress made in establishing the system of meteorological ob- 



