C‘334 ] 
eclipses of jupiter’s satellites : obferved 
with the fame telefcope, magnifying 100 times. 
In thefe eclipfes, I have endeavoured to make ufe 
of the method recommended by M. bailly, in a 
paper communicated to this fociety the la ft year, 
and printed in our Tranfatlions, Vol. LXIII. p. 185. 
The diameter of the aperture of my telefcope is 
3,6 inches j and the diaphragms I have made, have 
their apertures differing from each other in diameter, 
as near as may be, _L.th of an inch. When the air 
is fteady for any continuance, and uninterrupted 
with clouds, even though it be not perfectly clear, 
I fhould apprehend this method may be of confi- 
derable ufe in reducing the obfervations of different 
perfons to fome ftandard : but when there are flying 
clouds, or any changes in the atmofphere, during the 
obfervation, it cannot be fatisfa&ory ; and at iuch 
times may be fcarce worth attempting) unlefs for 
the fake of rendering fuch pra&itioners as myfeif 
more expert, when the air is more favourable to 
their endeavours. 
I have, in fome of thefe eclipfes, as well as the 
preceeding occultations, fet down the altitude of 
the objeCt ; as that may fometimes be of ufe, in con- 
fidering the ftate of the obfervation. But it fhould 
be remembered, that thefe altitudes are not taken 
with any great precision. In thefe eclipfes, as in the 
occultations, I have fupprefled thofe obfervations 
which appeared doubtful; they tend only to 
; miflead.. 
* 77 * 
