84. View of the Progress of 



Art. VI. View of the Progress of Astronomy in Germany, 

 ybr 1818. ExtractedfromLindenau^s Journal. 



i. January and February, 1818. 



I. Laplace on the Application of the Theorij of Probabilities to 

 Geodetical Operations. 



From the Annales de Chimie. 



II. Littroiv on Observations with the Transit Instrument. 



Taking the instrument of Kbnigsberg, as employed by Bessel, 

 for a favourable specimen, Professor Littrow examines the mean 

 error of a great number of observations of transits of a star, and 

 he infers that the mean error of a single observation was about 

 ",12 in time, the most probable error ",10 ; the most probable 

 error of the mean of the observations on three wires ",058 ; with 

 five wires, the most probable error would have been ",045 ; and 

 with seven ",038. He infers that it is perfectly right to carry our 

 calculations, in general, to hundredths of seconds of time ; but 

 that we cannot be sure even of tenths of- seconds of space, unless 

 we employ as many as 200 wires ; and that we may, in almost 

 all cases, be satisfied with calculating to a single second, when 

 space is concerned, without adverting to its fractions. 



For determining the rate of a clock within half a second of 

 space, it appears that 15 pairs of stars must be observed on two 

 successive days, the most probable error of a single observation 

 of this kind being ,13 in time. 



The difference of two right ascensions of stars is also ascer- 

 tained by a single observation within ",13 as the most probable 

 error : so that to obtain the precision of ",01 in time, we require 

 about 170 observations. The clock, however, does not appear to 

 have been remarkably good. 



For the immediate right ascensions, or the accuracy of the 

 setting of the clock, the most probable error of 275 observations 

 was ,"18 in time ; so that for a second of space we should re- 

 quire at least a comparison of 7 observations, and more than 

 J 00, to be tolerably certain within ' | ; consequently, the em- 



