244 History of Astronomy for the Year 1805: 
perceived any ring; and another upon the causes which 
make the mirrors of a telescope change their form. 
In the Transactions for 1804 he speaks of the double stars 
which for 25 years seem to have experienced some varia- 
tions, particularly in respect to the angles of distance with 
the ecliptic, which makes him think that they turn but so 
slowly that it is difficult to affirm it. He has seen one part 
conceal the other in one of these double stars. 
M. Delambre’s tables of the sun, and M. Burg’s tables 
of the moon, have been finished and presented. M. De- 
lambre has revised the tables of the moon in such a manner 
that all the equations are additive ; which will save time, 
and diminish the risk of making errors. These tables are 
about to appear. 
The new table of refractions of M. de Laplace, which 
appears with the tables of the sun, gives six-tenths of the 
second at 45° more than that of Bradley; but M..de La- 
place informs astronomers that discordances have been often . 
found between the two solstices, from having placed the 
thermometer within an observatory, instead of placing it 
outside, but out of sunshine. 
The observations of the two solstices,and the two equi- 
noxes, made by M. Delambre, with a repeating circle, du- 
ring several days, have confirmed the epochs of the  obli- 
quity of the ecliptic, which he uses in his new tables. 
Epoch for 1800, 9° 10° 23’ 32: 6”, less by two 2” than in 
his former tables. Mean obliquity, 23° 27’ 57” ; greater by 
4” than in the tables of my third edition, which have been 
hitherto made use of. 
M. Delambre has finished the printing of the first volume 
of the great work on the meridian, in 750 pages: it is en- 
titled Base du Systeme Métrique Decimal; or, Mesure de 
Arc du Meridien. It contains all the triangles formed 
from Dunkirk to Barcelona. The second volume will 
contain the bases, the azimuths, the latitudes, and the 
calculations of the triangles. Perhaps there will be a third 
volume afterwards added. 4 
The new tables of Jupiter and Saturn, calculated by M. Bou- 
vard, haye been finished, and they are about to be printed. 
Those 
