[ 5*9 ] 
nomers, of the prefent age, of the time, when they are 
to expedt the tranfit : Whereas thofe, who fhall make 
life of Caffini’s tables, from which our ephemerides, 
and thofe of Italy, are calculated, will be miftakm 
no lefs than 4 hours ; the tranfit being to happen fo 
long fooner by thofe tables, than by Dr. Halley's. 
This difference appeared to me confiderable enough 
to deferve, that aflronomers fhould be acquainted 
with it > and this I am preparing to do by an adver- 
tifement, which will be immediately published. 
In the mean time, I thought it proper to fend to 
the Eaft Indies, to endeavour to procure from thence 
exadt obfervations of the tranfit in thofe places, where 
the whole duration may be obferved. The emerfion 
may be feen, in part of North America, a little after 
fun- rife ; and fince an accurate obfervation, which 
may be made there, will ferve to determine the pa- 
rallax of the Sun, if thofe obfervations are compared 
with the others to be made in the Eaft Indies, I am 
obliged to write to you, to requeft you to recommend 
to all thofe, who fhall be able, and have an opportu- 
nity to make this obfervation, in your Englifh co- 
lonies, to attend to it ; and that the Royal Society 
will likewife make ufe of their intereft for that 
purpofe. 
I have found, that at Cambridge near Boflon, 
where Mr. Winthrop obferved the tranfit in 1740, 
Mercury's emerfion from the Sun will be at 5 h 47' in 
the morning; which is yi minutes after fun-rife : 
At New York it will be yh 32', which is 34 minutes 
after fun-rife ; in other places, in the neighbourhood, 
it will be, in proportion, nearer or farther from fun- 
rife j as will be eafily calculated. But it were to be 
wi fil’d. 
