2 ASTRONOMICAL AnD 
of folar eclips and occultations of fixed flars by the moon, 
every method which can be difcovered, to fhorten the work, 
or maké it more eafy, muft be of utility. In calculating thete 
parallexes, it is neceflary to find the altitude and longitude of 
the nonagefimal degree of the-ecliptic. -As I have given fome 
attention to this fubject, I take the liberty, Sir, of enclofing to 
you a paper, containing a method of finding thefe prerequifites, 
different from any that I have happened to meet with, and (to 
me indeed) taking the whole procefs together, eafier, if not 
fhorter. It is deduced from a projection which muft make the 
method very obvious, to thofe acquainted with the {phere and 
with fpheric trigonometry. You will find an appendix upon 
the longitude of Cambridge... If you think proper to commu- 
n:cate the whole to the Academy, you have my confent. 
, zx 
I am, 
with the greateft refpet, &c. — — 
: x: ien » = : = $ Se xi tired acti vae : iin 
Cambridge, Auguft 4, 1783. 3 
DEFINITIONS, 
the equator, which culminates, or is in the meridian of any pàr- 
-ticular place, at a given time, and is found by adding the given 
Apparent time, reckoned aftronomically, to the fun's right af- 
cenfion, calculated for the fame time. Or, it may be found, 
by reducing the given apparent time to mean time, and adding 
it to the fün's mean longitude. But, if the hours aré reckoned 
according to civil time, we muft take the difference between 
! ; the 
1. THE right afcenfion of the mid-heaven is that point of 
