Natui'al PhkloHo^hij, — Agronomy. 
tion of the celebrated M. Gauss, is now provided with fixed 
instruments of high perfection, viz. a meridian -circle Rep- 
sold ; and another meridian-circle and transit-instrument by 
Reichenbach. These instruments, which are cifcumstantially 
described in the literary Gazette of Gottingen, (Gbttmgishe 
Gelchrte Anzeigen, 1818, p. 1^57; 1819^ p. 1665; 18^0, 
p. 905.), are so perfect, that the two last shew, under favour- 
able circumstances, at noon, stars of the fourth or even of the 
fifth magnitude. A regular course of observations is carried on 
at the observatory. M. Gauss, in concert with the astrono- 
mers of four or five other observatories, has been carrying on 
for some time a series of observations upon a fixed plan. The 
object of that plan is to determine the difference between the 
meridians of the observatories, by observing the right ascensions 
of the moon when she passes over the meridian. The moon is 
usually compared each night from the first quarter till after the 
full with threes tars (previously selected and before announced to 
the five astronomers) near the moon, and almost on the same 
parallel. The harmony of the results has been greater than 
was expected, and is in some cases very surprising, as in the 
following examples : 
Meridian Difference between Gottingen and Konigsberg. 
Difference of Meridian. 
1820, Feb. 22. two stars, . . , 42' 10^8 
April 21. one star, - - - - 42 12 .8 
22. three stars, - - - 42 13 .6 
23. two stars, - - - 42 14 .8 
26. two stars, - - - - 42 10 .0 
Meridian Diff&)'ence between Gottingen and Dorpat. 
1820, April 22. three stars, - - - 67' 6".7 
23. two stars, - - - - 67 8 .6 
25. two stars, - - - - 67 5 .3 
2. Comet of 1819* — This comet is expected to arrive at its 
next perihelion about the middle of May 1822, but it will be 
scarcely visible at that time in any part of Europe. Before it 
reaches its perihelion, it will be too distant from the Earth, and 
afterwards it wiU be too far to the south to be seen in Europe. 
In the southern hemisphere, however, it will be finely seen, and 
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