1853.] 



DAVIS'S EEPORT ON THE NAUTICAL ALMANAC. 



Davis's Report on the Nautical Almanac* 



Our readers may not be aware that the American Nautical 

 Ahnanac, establislied by Congress some three years since, and 

 plared under the super\ision of the Na\'y Department, is ah'eady 

 so far advanced, under the able superintendence of Lieut. C. H. 

 Davis, tltat a few weeks will witness the appearance of the first 

 volume, computed for the year 1855. The ability and position 

 of the gentlemen charged with the execution of the woi-k, affords 

 the best reason for expecting a publication which shall materially 

 add to the scientific reputation of our country. 



The attention of our legislators has recently been recalled to 

 the subject by a series of most singular resolutions offered in the 

 United States Senate by a distinguished member of that body, 

 whose philanthropy is evidently more enlarged than his 

 astronomy. The resolutions of inquir}-, with the answers appended 

 to each by Lieut. Davis, were as follows : — ■ 



1. That the Secretary of the Nav>j be instructed to inform 

 Hie Senate where, and at what observatory, the observations and 

 calculations for the'-' Nautical Almanac'" are made. 



This inquiry comprises several distinct interrogatories, which, 

 with your permission, I will answer separately. 



The calculations of the Nautical Alm&nac are made at no 

 observatory, and have no direct connection with or dependence on 

 the current duty of any particular observatory. The daily duties 

 of observatories, and of offices like this of the "Nautical Almanac 

 and Astronomical Ephemeris," are perfectly distinct from each 

 other. The business of the observatory proper is to record events 

 and appearances, and to make the calculations requisite to render 

 these records immediately useful to the astronomer; it also 

 endeavours to add to the sum of knowledge bv the discovery of 

 new facts, and the observation of new truths and phenomena, as 

 exemplified by the frequent discovery of planets and comets, and 

 the constant observation of those, the periods of which are still 

 to be investigated; by the study of the nature of comets, — 

 of the rings of Satm'n, — of the comparative brightness of stars 

 and planets, <fec. 



The business of the office of a " Nautical Almanac and Astro- 

 nomical Ephemeris " is to predict, one or more years in advance, 

 the events and phenomena, the actual occurrence of which the 

 observatory records, and which the navigator compares, observes, 

 and calculates, while on the otherwise pathless sea, in order to pass 

 in safety from country to country. 



The calculations of the Nautical Almanac are made principally 

 at Cambridge, the residence of the present superintendent, where 

 the printing of the work can be conducted most expeditiously, 

 most economically, and, what is still more important, most accu- 

 rately : and where convenient reference can be had to the best 

 scientific libraries of the country, an indispensable aid in laying 

 the permanent foundation of a work of this magnitude and 

 importance. 



But as the superintendent of the almanac has succeeded in 

 engaging the limited sersdces of some distinguished mathemati- 

 cians and astronomers in other parts of the Union, a portion of 

 the computations have been made elsewhere; for example: by 

 Professor Winlock, of Kentucky ; by Mr. Sears C. Walker, of 

 Washington ; by Professor Kendall, of Philadelphia ; by Professor 

 Smith, of the Wesleyan University, at Middletown ; and by Miss 

 Mitchell, of Nantucket. 



The observations used by the Nautical Almanac," that is the 

 observations on which the fundamental laws of the astronomical 

 prediction are based, have not been made £it one observatory, but 



• Silliman's Journal. 



at all observatories ; not at one place, but at all places of correct 

 and well-attested obsei'vation on the globe ; not at one time, but 

 in all times of authentic history. 



2. Why the same are not made at the National Observatory 

 at Washington? 



Whenever, in the progress of theoretical information, or in 

 consequence of entirely new discoveries, or for the purpose of 

 anticipating the official publication of printed volumes, it has been 

 occasionally desirable and expedient to have recourse to an 

 observatoi-y, the National Observatory at Washington is the only 

 one to which the superintendent of the almanac has applied for 

 information. 



The superintendent of the National Observatory has been 

 requested, for example, to make some meridian observations of 

 stars of comparison, which were used in the reduction of those 

 observations of the planet Mars which have been made during the 

 last hundred years at the Greenwich observatory ; to test by 

 , immediate observations the accuracy of the elements of the new 

 planet Iris ; to furnish from the records of the observatory certain 

 information in anticipation of the next printed volume of the 

 " Washington Observations;" and to direct the attention of the 

 observers towards the new planets discovered since the year 1 827, 

 concerning which astronomical history supplies, of course, no 

 information, and concerning which all our knowledge is to be 

 gleaned from future observation. 



But it is the printed and published transactions of this and 

 other observatories, in which the observations, &c., are given to 

 the world in their reduced and complete and final form, that are 

 employed in the large computations of the almanac, and not the 

 separate observations made at the various instruments from day 

 to day, in the prosecution of a great scientific enterprise. 



3. What expenses are necessary therefor, except the pay of 

 the svperintendent? 



The pay of computers, the cost of publication, including com- 

 position, ]3ress-work, and correction ; paper, books, &c., &c, ; the 

 expense of stereotyping; the printing of auxiliary tables for com- 

 putation, of blanks, of instructions, and mathematical formulas 

 and methods. 



4. What progress has been made towards mahing a Nautical 

 Almanac ? 



The fii-st volume is nearly completed, and its printing far 

 advanced. All the main and heavy computations are done. 



5. For how long a period the calculations of the first almanac 

 are expected to extend? 



For a period of one year; the first number of the almanac will 

 be published in the year 1852, for the year 1855. 



6. Whether it is necessary to the perfection of the Nautical 

 Almanac to make observations at more than one observatory ; 

 and, if so, are they made at two observatories ; and, if so, at 

 what two ? 



The reply to this question is partly comprised in the reply to 

 the first question. 



If all the established observatories in Europe and elsewhere 

 published to the world the results of their laboure in the same 

 convenient, complete, and elegant form as the observatories at 

 Washington and Greenwich, they would not be too numerous for 

 the wants of those astronomers who devote their attention to the 

 improvement of the theories of planetary motion. And it is from 

 these published volumes, of -whatever date, that the almanac 

 derives its useful and serviceable facts and information. 



