C 476 ] 
If the quantity of the fun’s diameter, and the lead 
didance of the centers were very exadtiy known, 
tha Sun’s parallax might fafely be determined by 
comparing the duration of the tranfit as obferved at 
different places with the duration as fuppcfed to be 
ieen from the earth’s center. According to this me- 
thod, fuppofmg the lead didance of the centers to be 
9 '. 29" 4 -, which is a mean between the Greenwich 
Shirburn and Paris obfervations, and the difference of 
the femidiameters of the Sun and Venus— 9 1 6", 4, 
the duration as obferved at Tobolfki was more than 
10 minutes fhorter than if feen without parallax; at 
Tornea 0 , at Stockholm, at Cajanehurg, at Adracan, 
and indeed in almod every part of Europe and Alia, 
the duration was conliderably Shortened ; and if a 
number of good obfervations made in feveral of thofe 
parts were procured, the Quantity of the Sun’s, 
parallax might be well enough afcertained, as the 
difference in duration for a difference of one fecond 
in the Sun’s parallax will be found very confi- 
derable. 
Tho’ this method fhould not be pradtifed, unlefs 
the neceffary requifites for the computation be known 
with fome degree of precifion, I have ventured to 
compare the durations obferved chiefly in the north- 
ern parts of Europe, and fome in Ada, with the du- 
ration, as feen from the earth’s center, — 5 h . 59'. 1 9 ", 1 o 
mean time, or 5 h . 59'. 1 6", 64 apparent time, and cal- 
culated from the elements above mentioned. 
Places 
