160 EIGHTH ANNUAL REPORT OP 



of the Board, for facilitating the calculation of the time of appearance 

 of occultations of the fixed stars by the moon. The object of these 

 tables is to assist in the accurate determination of the longitude of 

 important places on the continent of North America, and their value 

 has been attested by the recommendation of some of the most distin- 

 guished astronomers of this country. The accurate establishment of 

 the longitude of any place renders it a landmark to the surveyor, the 

 geographer, and the astronomer, and furnishes a most important ele- 

 ment in determining its relative position on the map of the country. 

 The observation of occultations affords one of the most ready means 

 of solving this most difficult practical problem. The tables were cal- 

 culated at the expense and under the direction of the Institution, and 

 were sent to all persons known to be interested in practical astronomy, 

 with a request that the observations which might be made in connex-^ 

 ion with them might be sent to the Institution for computation, or pub- 

 lished in some accessible journal. These tables have been so well 

 received by astronomers, that, with the concurrence of the Executive 

 Committee, I have ventured to order the computation of a set of the 

 same kind on a more extensive scale for the j^ear 1849. Copies of 

 these will be sent to United States officers on the coast of Oregon and 

 California, and will be distributed among all the other observers in this 

 country. They will be found of much practical importance to the 

 corps engaged by the general government in establishing the boundary 

 lines of our new possessions. It is hoped that the remuneration 

 allowed for the labor of computing these tables will not be considered 

 extravagant, when it is mentioned that it has occupied the whole time 

 of Mr. Dowues lor nearly six months, at the rate of eight hours a day. 



With tlie concurrence of the Executive Committee, I have also pub- 

 lished an ephcmeris of the planet Neptune, or in other words, a table 

 indicating its position in the heavens during each day of the present 

 year, by which those interested in astronomy are enabled readily to 

 find the place of the new planet in the heavens, or the direction in 

 which the telescope must be pointed in order to observe it. Copies of 

 this have been sent to all the principal astronomers in the world, and 

 it has received the highest commendation. It was calculated by Mr. 

 S. C. Walker from the orbit deduced by himself, a full account of 

 which forms one of the papers of the second volume of the Contribu- 

 tions. It is the first accurate ephemeris which has ever appeared of 

 this newly discovered member of our solar system. 



An appropriation of one thousand dollars was made at the last meet- 

 ing of the Board for the commencement of a series of meteorological 

 observations, particularly with reference to the phenomena of American , 

 storms. According to the estimate of Prof Loomis, appended to my 

 last report, three thousand dolkirs will be required for the purpose of 

 reducing this part of our plan to practice. It is hoped that one thou- 

 sand dollars in addition will be appropriated this year, and an equal 

 sum the next, so that, at the end of that time, we shall be prepared for 

 full operation. At the last session of Congress an appropriation was 

 made for meteorology under the direction of the Secretary of the Navy ; 

 and in order that the observations thus established may not interfere 

 with those undertaken by the Smithsonian Institution, that officer has 



