78 abstracts: astronomy 



1867 the results were sent to the Observatory ready for printing. In 

 1872 the Mural Zones were published with an introduction by Prof. 

 Asaph Hall, U.S.N., and later in the same year the Meridian Transit 

 Instrument Zones were similarly published, In 1873 the remaining 

 Meridian Circle Zones were published and in closing the introduction 

 Professor Hall says, "On account of the inexperience of some of the 

 observers and the lack of good organization these observations contain 

 many errors, and the whole work needs a careful revision. In order to 

 facilitate this revision, and the final arrangement of the stars into a cata- 

 logue, a list of 415 stars has been selected from the Mural Zones, and 

 these stars will be observed anew with the Pistor and Martins Meridian 

 Circle. With this new data, combined with the results obtained from 

 southern observatories, it is hoped that we may have the means of deriv- 

 ing from these zones a valuable catalogue of southern stars." This 

 particular plan of reducing the zone observations, however, was never 

 executed. 



In 1892, as a preliminary step to the formation of a catalogue all the 

 observations were copied on cards under the direction of Prof. J. R. 

 Eastman, U.S.N. 



In 1902, a considerable number of unreduced zone observations were 

 found in the files of the observatory. They were reduced under the direc- 

 tion of Prof. F. B. Littell, U.S.N., and they furnish about 6000 of the 

 44900 observations in this volume. Nearly all of these observations 

 were taken in 1851 and 1852 using the then newly introduced method of 

 the electric chronograph for recording transits. It is interesting to 

 note that the increase of accuracy due to this change was, as is generally 

 conceded to be the case, not great for a transit over a single thread, 

 the results of these observations indicating an advantage of about 6 

 per cent in accuracy for the chronographic method. However, as five 

 threads could be observed by this method in the time taken to secure two 

 threads by the eye and ear method, and as many of the earlier observa- 

 tions were restricted to but one or two threads on account of lack of 

 time, the real gain from the introduction of the chronographic registra- 

 tion by which five threads were usually secured was much greater. In- 

 deed for this particular work, as it was done, it is likely that the increase 

 of accuracy due to the use of the chronographic method averaged nearly 

 75 per cent. With the transit instrument in 1851-52, the declinations 

 were obtained by means of chronographic transits over sets of oblique 

 threads inclined at an angle of 45° to the right ascension threads. From 

 a comparison of the results however, no gain was shown by this method 



