s 2,6 Mr. herschel’s Agronomical Obfervatiom 
Thefe feveral refults are fo exceedingly various, that it is evi- 
dent Jupiter is not a proper planet for the critical purpofe of a 
comparative view of the diurnal motions ; nor can this great 
variety proceed from any inaccuracy in the observations : for, 
in my opinion, it is not well .poffi.ble to make a miffake in the 
htuation of a fpot that ffiall amount to fo much as five minutes 
of time. The obfervation of April 23, 1779, was made with 
a view to afcertain this point, when it was found that five mi- 
nutes of time made a fenfible difference in the fituation of a 
fpot when near the center. 
If we reduce the fy nodical revolutions to fydereal ones, the 
refult will be fo little different from the above, that I have not 
thought it worth while to do it in this place. By a comparifon 
of the different periods it appears, that a fpot which is carried 
about in the atmofphere of Jupiter generally buffers an accelera- 
tion, or, which is the fame thing, performs its revolutions by 
degrees in lefs time than it did at fir if ; for the fpot obferved in 
3778 moved at the following rates. From February 25. to 
March 2. in 9 h. 55' 2.0" ; to March 3. nearly the fame ; to 
March 14. in 9 h. 55' 4" ; from March 2. to March 3. in 
9 h. 55' 40" ; to March 14. in 9 h. 54' 58" ; from March 3. 
to March 14. in 9 h. 54' 53'h In 1779 a fpot moved from 
April 14, to April 19. at the rate of 9I1. 51' 45 '' ; to April 23. 
in 9 h .51' 24" ; and from April 1 9. to April 24. in 9 h. 50' 48" ; 
all which is agreeable enough to the theory of equatorial winds, 
fmce it may probably take up fometime before a fpot can acquire 
a fufficient velocity to go as faff as thefe winds may blow. And, 
by the by, if Jupiter’s fpots fhould be obferved in different 
parts of his year, and be found in fome to be accelerated, in 
others to be retarded, it would almoft amount to a demonftra- 
tion of his monfoons and their periodical changes ; but if his 
~ axis 
